diff --git a/sdk/cpp/core/tests/models/ydktest-sanity@2015-11-17.yang b/sdk/cpp/core/tests/models/ydktest-sanity@2015-11-17.yang
index 0b4711cdb..e371c4474 100644
--- a/sdk/cpp/core/tests/models/ydktest-sanity@2015-11-17.yang
+++ b/sdk/cpp/core/tests/models/ydktest-sanity@2015-11-17.yang
@@ -579,7 +579,7 @@ module ydktest-sanity {
     }
   }
 
-    grouping three-level-w-list-at-two {
+  grouping three-level-w-list-at-two {
     container inbtw-list {
       description "config for one_level list data";
       list ldata {
@@ -645,6 +645,21 @@ module ydktest-sanity {
     }
   }
 
+  grouping two-key-list {
+    list two-key-list {
+        key "first second";
+        leaf first {
+            type string;
+        }
+        leaf second {
+            type uint32;
+        }
+        leaf property {
+            type string;
+        }
+    }
+  }
+
   container runner {
 
     //container at 1,2,3 nested level
@@ -666,6 +681,8 @@ module ydktest-sanity {
 
     uses not-supported;
 
+    uses two-key-list;
+
     container runner-2 {
 
        presence "Runner-2 is presence controlled";
diff --git a/sdk/python/core/tests/test_entity_diff.py b/sdk/python/core/tests/test_entity_diff.py
new file mode 100644
index 000000000..d46846e0c
--- /dev/null
+++ b/sdk/python/core/tests/test_entity_diff.py
@@ -0,0 +1,211 @@
+""" 
+Test cases for YDK entity_diff.
+
+
+"""
+
+from __future__ import print_function
+
+import unittest
+
+from ydk.types import entity_to_dict, entity_diff
+
+from ydk.models.ydktest import ydktest_sanity as ysanity
+
+# from test_utils import enable_logging, print_entity, print_data_node
+
+
+def check_empty_str_value(v):
+    if isinstance(v, str) and v.__len__() == 0:
+        v = 'exists'
+    return v
+
+
+def print_dictionary(legend, ent_dict, key_width=70):
+    print("\n------> DICTIONARY%s:" % legend)
+    for n, v in sorted(ent_dict.items()):
+        print("%s: %s" % (n.rjust(key_width), check_empty_str_value(v)))
+
+
+def print_diffs(diff, key_width=70):
+    print("\n------> DIFFS:")
+    for key in diff:
+        value = diff[key]
+        print("%s: %s vs %s" % (key.rjust(key_width), check_empty_str_value(value[0]), check_empty_str_value(value[1])))
+
+
+class EntityDiffTest(unittest.TestCase):
+
+    def test_entity_diff_two_key(self):
+        runner = ysanity.Runner()
+        l_1 = ysanity.Runner.TwoKeyList()
+        l_2 = ysanity.Runner.TwoKeyList()
+        l_1.first, l_2.first = 'f1', 'f2'
+        l_1.second, l_2.second = 11, 22
+        l_1.property, l_2.property = '82', '83'
+        runner.two_key_list.extend([l_1, l_2])
+        
+        ent_dict = entity_to_dict(runner)
+        self.assertEqual(len(ent_dict), 4)
+        print_dictionary('-LEFT', ent_dict)
+
+        runner2 = ysanity.Runner()
+        l_1, l_2 = ysanity.Runner.TwoKeyList(), ysanity.Runner.TwoKeyList()
+        l_1.first, l_2.first = 'f1', 'f2'
+        l_1.second, l_2.second = 11, 22
+        l_1.property, l_2.property = '82', '83'
+        runner2.two_key_list.extend([l_1, l_2])
+
+        diff = entity_diff(runner, runner2)
+        self.assertEqual(len(diff), 0)
+
+        l_1.property = '83'
+        print_dictionary('-RIGHT', entity_to_dict(runner2))
+        diff = entity_diff(runner, runner2)
+        self.assertEqual(len(diff), 1)
+        print_diffs(diff)
+
+    def test_entity_diff_two_key_not_equal(self):
+        runner = ysanity.Runner()
+        l_1, l_2 = ysanity.Runner.TwoKeyList(), ysanity.Runner.TwoKeyList()
+        l_1.first, l_2.first = 'f1', 'f2'
+        l_1.second, l_2.second = 11, 22
+        l_1.property, l_2.property = '82', '83'
+        runner.two_key_list.extend([l_1, l_2])
+
+        ent_dict = entity_to_dict(runner)
+        self.assertEqual(len(ent_dict), 4)
+        print_dictionary('-LEFT', ent_dict)
+
+        runner3 = ysanity.Runner()
+        l_1, l_2 = ysanity.Runner.TwoKeyList(), ysanity.Runner.TwoKeyList()
+        l_1.first, l_2.first = 'f1', 'f3'
+        l_1.second, l_2.second = 11, 22
+        l_1.property, l_2.property = '82', '84'
+        runner3.two_key_list.extend([l_1, l_2])
+
+        ent_dict = entity_to_dict(runner3)
+        self.assertEqual(len(ent_dict), 4)
+        print_dictionary('-RIGHT', ent_dict)
+
+        diff = entity_diff(runner, runner3)
+        self.assertEqual(len(diff), 2)
+        print_diffs(diff)
+
+    def test_entity_to_dict_aug_onelist(self):
+        runner = ysanity.Runner()
+        e_1 = ysanity.Runner.OneList.OneAugList.Ldata()
+        e_2 = ysanity.Runner.OneList.OneAugList.Ldata()
+        e_1.number = 1
+        e_1.name = "e_1.name"
+        e_2.number = 2
+        e_2.name = "e_2.name"
+        runner.one_list.one_aug_list.ldata.extend([e_1, e_2])
+        runner.one_list.one_aug_list.enabled = True
+
+        ent_dict = entity_to_dict(runner)
+        self.assertEqual(len(ent_dict), 5)
+        print_dictionary('', ent_dict, 60)
+
+    def test_entity_to_dict_enum_leaflist(self):
+        runner = ysanity.Runner()
+        runner.ytypes.built_in_t.enum_llist.append(ysanity.YdkEnumTestEnum.local)
+        runner.ytypes.built_in_t.enum_llist.append(ysanity.YdkEnumTestEnum.remote)
+
+        ent_dict = entity_to_dict(runner)
+        self.assertEqual(len(ent_dict), 2)
+        print_dictionary('', ent_dict, 50)
+
+    def test_entity_diff_number_leaf(self):
+        runner1 = ysanity.Runner()
+        runner1.ytypes.built_in_t.number8 = 23
+
+        ent_dict = entity_to_dict(runner1)
+        self.assertEqual(len(ent_dict), 1)
+        print_dictionary('-LEFT', ent_dict, 50)
+
+        runner2 = ysanity.Runner()
+
+        ent_dict = entity_to_dict(runner2)
+        self.assertEqual(len(ent_dict), 0)
+        print_dictionary('-RIGHT', ent_dict, 50)
+
+        diff = entity_diff(runner1, runner2)
+        self.assertEqual(len(diff), 1)
+        print_diffs(diff, 50)
+
+    def test_entity_to_dict_presence(self):
+        runner = ysanity.Runner()
+        runner.runner_2 = ysanity.Runner.Runner2()
+        runner.runner_2.some_leaf = 'some-leaf'
+
+        ent_dict = entity_to_dict(runner)
+        self.assertEqual(len(ent_dict), 2)
+        print_dictionary('-LEFT', ent_dict, 40)
+
+        runner_ = ysanity.Runner()
+        ent_dict = entity_to_dict(runner_)
+        self.assertEqual(len(ent_dict), 0)
+        print_dictionary('-RIGHT', ent_dict, 40)
+
+        diff = entity_diff(runner, runner_)
+        self.assertEqual(len(diff), 1)
+        print_diffs(diff, 40)
+
+    def test_entity_diff_two_level_list(self):
+        r_1 = ysanity.Runner()
+        e_1, e_2 = ysanity.Runner.TwoList.Ldata(), ysanity.Runner.TwoList.Ldata()
+        e_11, e_12 = ysanity.Runner.TwoList.Ldata.Subl1(), ysanity.Runner.TwoList.Ldata.Subl1()
+        e_1.number = 21
+        e_1.name = 'runner:twolist:ldata['+str(e_1.number)+']:name'
+        e_11.number = 211
+        e_11.name = 'runner:twolist:ldata['+str(e_1.number)+']:subl1['+str(e_11.number)+']:name'
+        e_12.number = 212
+        e_12.name = 'runner:twolist:ldata['+str(e_1.number)+']:subl1['+str(e_12.number)+']:name'
+        e_1.subl1.append(e_11)
+        e_1.subl1.append(e_12)
+        e_21, e_22 = ysanity.Runner.TwoList.Ldata.Subl1(), ysanity.Runner.TwoList.Ldata.Subl1()
+        e_2.number = 22
+        e_2.name = 'runner:twolist:ldata['+str(e_2.number)+']:name'
+        e_21.number = 221
+        e_21.name = 'runner:twolist:ldata['+str(e_2.number)+']:subl1['+str(e_21.number)+']:name'
+        e_22.number = 222
+        e_22.name = 'runner:twolist:ldata['+str(e_2.number)+']:subl1['+str(e_22.number)+']:name'
+        e_2.subl1.append(e_21)
+        e_2.subl1.append(e_22)
+        r_1.two_list.ldata.append(e_1)
+        r_1.two_list.ldata.append(e_2)
+
+        ent_dict = entity_to_dict(r_1)
+        self.assertEqual(len(ent_dict), 12)
+        print_dictionary('-LEFT', ent_dict, 80)
+
+        r_2 = ysanity.Runner()
+        e_1, e_2 = ysanity.Runner.TwoList.Ldata(), ysanity.Runner.TwoList.Ldata()
+        e_11, e_12 = ysanity.Runner.TwoList.Ldata.Subl1(), ysanity.Runner.TwoList.Ldata.Subl1()
+        e_1.number = 21
+        e_1.name = 'runner:twolist:ldata['+str(e_1.number)+']:name'
+        e_11.number = 211
+        e_11.name = 'runner:twolist:ldata['+str(e_1.number)+']:subl1['+str(e_11.number)+']:name'
+        e_12.number = 212
+        e_12.name = 'runner:twolist:ldata['+str(e_1.number)+']:subl1['+str(e_12.number)+']:name'
+        e_1.subl1.append(e_11)
+        e_1.subl1.append(e_12)
+        r_2.two_list.ldata.append(e_1)
+
+        ent_dict = entity_to_dict(r_2)
+        self.assertEqual(len(ent_dict), 6)
+        print_dictionary('-RIGHT', ent_dict, 80)
+
+        diff = entity_diff(r_1, r_2)
+        self.assertEqual(len(diff), 1)
+        print_diffs(diff, 50)
+
+
+if __name__ == '__main__':
+    suite = unittest.TestSuite()
+    testloader = unittest.TestLoader()
+    testnames = testloader.getTestCaseNames(EntityDiffTest)
+    for name in testnames:
+        suite.addTest(EntityDiffTest(name))
+    ret = not unittest.TextTestRunner(verbosity=2).run(suite).wasSuccessful()
diff --git a/sdk/python/core/ydk/_core/_dm_meta_info.py b/sdk/python/core/ydk/_core/_dm_meta_info.py
index 3bdc9a94b..0580887cd 100644
--- a/sdk/python/core/ydk/_core/_dm_meta_info.py
+++ b/sdk/python/core/ydk/_core/_dm_meta_info.py
@@ -130,7 +130,7 @@ def union_list(self):
         _list = []
         if self._mtype == REFERENCE_UNION:
             for union_member in self._members:
-                if (union_member._ptype == 'str'):
+                if union_member._ptype == 'str':
                     pattern = union_member._pattern
                 else:
                     pattern = union_member._range
diff --git a/sdk/python/core/ydk/providers/_encoder.py b/sdk/python/core/ydk/providers/_encoder.py
index 346ff0cb7..b2f76383e 100644
--- a/sdk/python/core/ydk/providers/_encoder.py
+++ b/sdk/python/core/ydk/providers/_encoder.py
@@ -60,7 +60,7 @@ def encode_to_xml(self, entity, root, optype, is_filter=False, validate=True):
                     elem.set('{' + xc + '}operation', get_yfilter_tag(yfilter))
             parent_ns = None
             current_parent = root
-            while current_parent != None and parent_ns is None:
+            while current_parent is not None and parent_ns is None:
                 parent_ns = current_parent.get('xmlns')
                 current_parent = current_parent.getparent()
 
diff --git a/sdk/python/core/ydk/types.py b/sdk/python/core/ydk/types.py
index 41e177c9f..3b3a69d2a 100644
--- a/sdk/python/core/ydk/types.py
+++ b/sdk/python/core/ydk/types.py
@@ -22,27 +22,29 @@
 from __future__ import absolute_import
 
 from decimal import Decimal, getcontext
-from .errors import YPYModelError
+from .errors import YPYModelError, YPYError
+from ._core._dm_meta_info import ANYXML_CLASS, REFERENCE_CLASS, REFERENCE_LIST, REFERENCE_LEAFLIST
+from ._core._dm_meta_info import REFERENCE_IDENTITY_CLASS, REFERENCE_UNION, ATTRIBUTE
 
 
 class DELETE(object):
-    '''Marker class used to mark nodes that are to be deleted
+    """Marker class used to mark nodes that are to be deleted
     Assign DELETE object to a mark a leaf for deletion.
-    A CRUD update operation will delete the leaf from the device it is on.'''
+    A CRUD update operation will delete the leaf from the device it is on."""
     pass
 
 
 class REMOVE(object):
-    '''Marker class used to mark nodes that are to be removed
+    """Marker class used to mark nodes that are to be removed
     Assign REMOVE object to a mark a leaf for deletion.
-    A CRUD update operation will delete the leaf from the device it is on.'''
+    A CRUD update operation will delete the leaf from the device it is on."""
     pass
 
 
 class MERGE(object):
-    '''Marker MERGE used to mark nodes that are to be merged
+    """Marker MERGE used to mark nodes that are to be merged
     Assign DELETE object to a mark a leaf for deletion.
-    A CRUD update operation will delete the leaf from the device it is on.'''
+    A CRUD update operation will delete the leaf from the device it is on."""
 
     def __init__(self, value=None):
         self._value = value
@@ -55,9 +57,9 @@ def set(self, value):
 
 
 class REPLACE(object):
-    '''Marker class used to mark nodes that are to be replaced
+    """Marker class used to mark nodes that are to be replaced
     Assign REPLACE object to a mark a leaf for deletion.
-    A CRUD update operation will delete the leaf from the device it is on.'''
+    A CRUD update operation will delete the leaf from the device it is on."""
 
     def __init__(self, value=None):
         self._value = value
@@ -68,10 +70,11 @@ def value(self):
     def set(self, value):
         self._value = value
 
+
 class CREATE(object):
-    '''Marker class used to mark nodes that are to be created
+    """Marker class used to mark nodes that are to be created
     Assign CREATE object to a mark a leaf for deletion.
-    A CRUD update operation will delete the leaf from the device it is on.'''
+    A CRUD update operation will delete the leaf from the device it is on."""
 
     def __init__(self, value=None):
         self._value = value
@@ -84,9 +87,10 @@ def set(self, value):
 
 
 class READ(object):
-    '''Marker class used to mark nodes that are to be read '''
+    """Marker class used to mark nodes that are to be read """
     pass
 
+
 class Empty(object):
     """
         .. _ydk_models_types_Empty:
@@ -283,12 +287,13 @@ def __getslice__(self, i, j):
         return ret
 
     def append(self, item):
-       super(YList, self).append(item)
-       item.parent = self.parent
+        super(YList, self).append(item)
+        item.parent = self.parent
 
     def extend(self, items):
-       for item in items:
-           self.append(item)
+        for item in items:
+            self.append(item)
+
 
 class YListItem(object):
     def __init__(self, item, parent, name):
@@ -411,3 +416,102 @@ def count(self, item):
             if i.item == item:
                 cnt += 1
         return cnt
+
+
+def get_absolute_path(entity):
+    path = entity._common_path
+    segments = path.split("/")
+    module = segments[1].split(':', 1)[0]
+    for i in range(2, len(segments)):
+        del_str = module + ':'
+        if del_str in segments[i]:
+            segments[i] = segments[i].replace(del_str, '')
+        else:
+            if ':' in segments[i]:
+                module = segments[i].split(':', 1)[0]
+    path = '/'.join(segments)
+    return path
+
+
+def get_name_leaf_data(entity):
+    leaf_name_data = {}
+    for member in entity._meta_info().meta_info_class_members:
+        value = getattr(entity, member.presentation_name)
+        if value is None or isinstance(value, list) and value == []:
+            continue
+
+        if member.mtype in [ATTRIBUTE, REFERENCE_IDENTITY_CLASS]:
+            leaf_name_data[member.name] = value
+        elif member.mtype == REFERENCE_LEAFLIST and isinstance(value, list):
+            for child in value:
+                key = "%s[.='%s']" % (member.name, child)
+                leaf_name_data[key] = ''
+    return leaf_name_data
+
+
+def get_children(entity):
+    children = {}
+    for member in entity._meta_info().meta_info_class_members:
+        value = getattr(entity, member.presentation_name)
+        if value is None or isinstance(value, list) and value == []:
+            continue
+
+        if member.mtype == REFERENCE_CLASS:
+            abs_path = get_absolute_path(value)
+            children[abs_path] = value
+        elif member.mtype == REFERENCE_LIST:
+            for child in value:
+                abs_path = get_absolute_path(child)
+                children[abs_path] = child
+    return children
+
+
+def entity_to_dict(entity):
+    edict = {}
+    abs_path = get_absolute_path(entity)
+    ent_meta = entity._meta_info()
+    if (hasattr(ent_meta, 'is_presence') and ent_meta.is_presence) or \
+            abs_path.endswith(']'):
+        edict[abs_path] = ''
+    leaf_name_data = get_name_leaf_data(entity)
+    for leaf_name, leaf_value in leaf_name_data.items():
+        if leaf_name not in entity.ylist_key_names:
+            edict["%s/%s" % (abs_path, leaf_name)] = leaf_value
+    for name, child in get_children(entity).items():
+        child_dict = entity_to_dict(child)
+        for n, v in child_dict.items():
+            edict[n] = v
+    return edict
+
+
+def entity_diff(ent1, ent2):
+    if ent1 is None or ent2 is None or type(ent1) != type(ent2):
+        raise YPYError("entity_diff: Incompatible arguments provided.")
+
+    diffs = {}
+    ent1_dict = entity_to_dict(ent1)
+    ent2_dict = entity_to_dict(ent2)
+    ent1_keys = sorted(ent1_dict.keys())
+    ent2_keys = sorted(ent2_dict.keys())
+    ent1_skip_keys = []
+    for key in ent1_keys:
+        if key in ent1_skip_keys:
+            continue
+        if key in ent2_keys:
+            if ent1_dict[key] != ent2_dict[key]:
+                diffs[key] = (ent1_dict[key], ent2_dict[key])
+            ent2_keys.remove(key)
+        else:
+            diffs[key] = (ent1_dict[key], None)
+            for dup_key in ent1_keys:
+                if dup_key.startswith(key):
+                    ent1_skip_keys.append(dup_key)
+    ent2_skip_keys = []
+    for key in ent2_keys:
+        if key in ent2_skip_keys:
+            continue
+        diffs[key] = (None, ent2_dict[key])
+        for dup_key in ent2_keys:
+            if dup_key.startswith(key):
+                ent2_skip_keys.append(dup_key)
+    return diffs
diff --git a/test/tests.sh b/test/tests.sh
index 8a19f5e26..8ee049026 100755
--- a/test/tests.sh
+++ b/test/tests.sh
@@ -67,6 +67,7 @@ function init_env {
     print_msg "init_env"
 
     YDKGEN_HOME=$(pwd)
+    print_msg "YDKGEN_HOME is set to ${YDKGEN_HOME}"
 
     PY_GENERATE="$1"
     PY_TEST="$2"
@@ -180,6 +181,7 @@ function py_sanity_ydktest_test {
 function py_sanity_ydktest_test_ncclient {
     print_msg "py_sanity_ydktest_test_ncclient"
     run_test sdk/python/core/tests/test_sanity_types.py
+    run_test sdk/python/core/tests/test_entity_diff.py
     run_test sdk/python/core/tests/test_sanity_errors.py
     run_test sdk/python/core/tests/test_sanity_filters.py
     run_test sdk/python/core/tests/test_sanity_levels.py
diff --git a/yang/ydktest/ydktest-sanity@2015-11-17.yang b/yang/ydktest/ydktest-sanity@2015-11-17.yang
index 0b4711cdb..e371c4474 100644
--- a/yang/ydktest/ydktest-sanity@2015-11-17.yang
+++ b/yang/ydktest/ydktest-sanity@2015-11-17.yang
@@ -579,7 +579,7 @@ module ydktest-sanity {
     }
   }
 
-    grouping three-level-w-list-at-two {
+  grouping three-level-w-list-at-two {
     container inbtw-list {
       description "config for one_level list data";
       list ldata {
@@ -645,6 +645,21 @@ module ydktest-sanity {
     }
   }
 
+  grouping two-key-list {
+    list two-key-list {
+        key "first second";
+        leaf first {
+            type string;
+        }
+        leaf second {
+            type uint32;
+        }
+        leaf property {
+            type string;
+        }
+    }
+  }
+
   container runner {
 
     //container at 1,2,3 nested level
@@ -666,6 +681,8 @@ module ydktest-sanity {
 
     uses not-supported;
 
+    uses two-key-list;
+
     container runner-2 {
 
        presence "Runner-2 is presence controlled";