BUG: resolved problem with DataFrame.equals() (#28839)

doc/source/whatsnew/v1.0.0.rst

@@ -451,6 +451,7 @@ Reshaping
 - Fix to ensure all int dtypes can be used in :func:`merge_asof` when using a tolerance value. Previously every non-int64 type would raise an erroneous ``MergeError`` (:issue:`28870`).
 - Better error message in :func:`get_dummies` when `columns` isn't a list-like value (:issue:`28383`)
 - Bug :meth:`Series.pct_change` where supplying an anchored frequency would throw a ValueError (:issue:`28664`)
+- Bug where :meth:`DataFrame.equals` returned True incorrectly in some cases when two DataFrames had the same columns in different orders (:issue:`28839`)
 
 Sparse
 ^^^^^^

pandas/core/internals/managers.py

@@ -1394,12 +1394,12 @@ def equals(self, other):
         if len(self.blocks) != len(other.blocks):
             return False
 
-        # canonicalize block order, using a tuple combining the type
-        # name and then mgr_locs because there might be unconsolidated
+        # canonicalize block order, using a tuple combining the mgr_locs
+        # then type name because there might be unconsolidated
         # blocks (say, Categorical) which can only be distinguished by
         # the iteration order
         def canonicalize(block):
-            return (block.dtype.name, block.mgr_locs.as_array.tolist())
+            return (block.mgr_locs.as_array.tolist(), block.dtype.name)
 
         self_blocks = sorted(self.blocks, key=canonicalize)
         other_blocks = sorted(other.blocks, key=canonicalize)

pandas/tests/internals/test_internals.py

@@ -1297,3 +1297,10 @@ def test_make_block_no_pandas_array():
     result = make_block(arr.to_numpy(), slice(len(arr)), dtype=arr.dtype)
     assert result.is_integer is True
     assert result.is_extension is False
+
+
+def test_dataframe_not_equal():
+    # see GH28839
+    df1 = pd.DataFrame({"a": [1, 2], "b": ["s", "d"]})
+    df2 = pd.DataFrame({"a": ["s", "d"], "b": [1, 2]})
+    assert df1.equals(df2) is False