diff --git a/dvc/repo/diff.py b/dvc/repo/diff.py
index 741fb3f0d..354f0693b 100644
--- a/dvc/repo/diff.py
+++ b/dvc/repo/diff.py
@@ -94,14 +94,15 @@ def _diff_file(self, target, diff_dct):
 
 
 def diff(self, target, a_ref=None, b_ref=None):
-    """
-    Gerenates diff message string output
-    input:
-    target - file/folder to check diff of
-    a_ref - first git ref/tag
-    b_ref(optional) - second git ref/tag
-    output:
-    string of output message with diff info
+    """Gerenates diff message string output
+
+    Args:
+        target(str) - file/directory to check diff of
+        a_ref(str) - first git tag
+        (optional) b_ref(str) - second git tag
+
+    Returns:
+        string: string of output message with diff info
     """
     diff_dct = self.scm.diff(target, a_ref=a_ref, b_ref=b_ref)
     msg = "dvc diff for '{}' from {} to {} \n\n".format(
diff --git a/dvc/scm/git/__init__.py b/dvc/scm/git/__init__.py
index 24434a937..c1c93e00c 100644
--- a/dvc/scm/git/__init__.py
+++ b/dvc/scm/git/__init__.py
@@ -266,7 +266,7 @@ class Git(Base):
         except (BadName, BadObject) as e:
             raise SCMError(e)
         if len(diff_obj) == 0:
-            msg = "Have not found file/folder '{}' in the commits"
+            msg = "Have not found file/directory '{}' in the commits"
             raise FileNotInRepoError(msg.format(file_name))
         return diff_obj[0], commits
 
@@ -279,11 +279,16 @@ class Git(Base):
             return None, None
 
     def diff(self, file_name, a_ref, **kwargs):
-        """
-        function for diff between two git tag commits
-        returns the dvc hash names of changed file/folder
-        file_name - file on which to calculate diff
-        returns dictionary with keys: (new_file, a_file_name, b_file_name)
+        """Method for diff between two git tag commits
+        returns the dvc hash names of changed file/directory
+
+        Args:
+            file_name(str) - file/directory to perform diff of
+            a_ref(str) - git reference
+            b_ref(str) - optional second git reference
+
+        Returns:
+            dict - dictionary with keys: (new_file, a_file_name, b_file_name)
         """
         diff_dct = {"equal": False}
         diff_obj, commit_refs = self._get_diff_obj(file_name, a_ref, **kwargs)
@@ -298,7 +303,7 @@ class Git(Base):
                 " to dvc?"
             )
             raise SCMError(msg.format(file_name))
-        # this function doesn't support an indicating of moved of a file/folder
+        # function doesn't support an indicating of moved of a file/directory
         diff_dct["new_file"] = diff_obj.new_file
         diff_dct["deleted_file"] = diff_obj.deleted_file
         diff_dct["a_hash"], diff_dct["a_fname"] = self._extract_fname(
diff --git a/tests/test_diff.py b/tests/test_diff.py
index 5c9223a60..7037ce422 100644
--- a/tests/test_diff.py
+++ b/tests/test_diff.py
@@ -60,7 +60,7 @@ class TestDiffDir(TestDvc):
         self.assertEqual(
             self.DATA_DIR + ".dvc",
             out["file_path"],
-            "path to file/folder is incorrect",
+            "path to file/directory is incorrect",
         )
 
 
@@ -82,7 +82,7 @@ class TestDiffFileNotFound(TestDiffDir):
         ) as context:
             self.dvc.scm.diff(self.unknown_file, self.a_ref)
         self.assertTrue(
-            "Have not found file/folder" in str(context.exception),
+            "Have not found file/directory" in str(context.exception),
             "scm raises with incorrect error message",
         )
 
@@ -93,4 +93,6 @@ class TestDiffFileNotFoundRepo(TestDiffFileNotFound):
             FileNotInRepoError, msg="diff with incorrect arg"
         ) as context:
             self.dvc.diff(self.unknown_file, a_ref=self.a_ref)
-        self.assertTrue("Have not found file/folder" in str(context.exception))
+        self.assertTrue(
+            "Have not found file/directory" in str(context.exception)
+        )