diff --git a/datafusion/physical-expr-common/src/binary_map.rs b/datafusion/physical-expr-common/src/binary_map.rs
index f320ebcc06b5..03ac4769d9d9 100644
--- a/datafusion/physical-expr-common/src/binary_map.rs
+++ b/datafusion/physical-expr-common/src/binary_map.rs
@@ -104,8 +104,9 @@ impl<O: OffsetSizeTrait> ArrowBytesSet<O> {
 /// `Binary`, and `LargeBinary`) values that can produce the set of keys on
 /// output as `GenericBinaryArray` without copies.
 ///
-/// Equivalent to `HashSet<String, V>` but with better performance for arrow
-/// data.
+/// Equivalent to `HashSet<String, V>` but with better performance if you need
+/// to emit the keys as an Arrow `StringArray` / `BinaryArray`. For other
+/// purposes it is the same as a `HashMap<String, V>`
 ///
 /// # Generic Arguments
 ///
diff --git a/datafusion/physical-expr-common/src/binary_view_map.rs b/datafusion/physical-expr-common/src/binary_view_map.rs
index bdcf7bbacc69..c6768a19d30e 100644
--- a/datafusion/physical-expr-common/src/binary_view_map.rs
+++ b/datafusion/physical-expr-common/src/binary_view_map.rs
@@ -88,8 +88,9 @@ impl ArrowBytesViewSet {
 /// values that can produce the set of keys on
 /// output as `GenericBinaryViewArray` without copies.
 ///
-/// Equivalent to `HashSet<String, V>` but with better performance for arrow
-/// data.
+/// Equivalent to `HashSet<String, V>` but with better performance if you need
+/// to emit the keys as an Arrow `StringViewArray` / `BinaryViewArray`. For other
+/// purposes it is the same as a `HashMap<String, V>`
 ///
 /// # Generic Arguments
 ///