diff --git a/python/pyspark/sql/window.py b/python/pyspark/sql/window.py
index e667fba099fb..d19ced954f04 100644
--- a/python/pyspark/sql/window.py
+++ b/python/pyspark/sql/window.py
@@ -44,6 +44,10 @@ class Window(object):
     >>> # PARTITION BY country ORDER BY date RANGE BETWEEN 3 PRECEDING AND 3 FOLLOWING
     >>> window = Window.orderBy("date").partitionBy("country").rangeBetween(-3, 3)
 
+    .. note:: When ordering is not defined, an unbounded window frame (rowFrame,
+         unboundedPreceding, unboundedFollowing) is used by default. When ordering is defined,
+         a growing window frame (rangeFrame, unboundedPreceding, currentRow) is used by default.
+
     .. note:: Experimental
 
     .. versionadded:: 1.4
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala b/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
index 1caa243f8d11..cd819bab1b14 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
@@ -33,6 +33,10 @@ import org.apache.spark.sql.catalyst.expressions._
  *   Window.partitionBy("country").orderBy("date").rowsBetween(-3, 3)
  * }}}
  *
+ * @note When ordering is not defined, an unbounded window frame (rowFrame, unboundedPreceding,
+ *       unboundedFollowing) is used by default. When ordering is defined, a growing window frame
+ *       (rangeFrame, unboundedPreceding, currentRow) is used by default.
+ *
  * @since 1.4.0
  */
 @InterfaceStability.Stable