Improve documentation of 'seq-intersection'

* doc/lispref/sequences.texi (Sequence Functions):
* lisp/emacs-lisp/seq.el (seq-intersection): Clarify the
documentation of 'seq-intersection'.  (Bug#79844)

2 files changed, 6 insertions, 5 deletions

diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi
index 2f7c6876a8f..2b1db79e07b 100644
--- a/doc/lispref/sequences.texi
+++ b/doc/lispref/sequences.texi
@@ -1109,10 +1109,11 @@ instead of the default @code{equal}.
 @defun seq-intersection sequence1 sequence2 &optional function
 @cindex sequences, intersection of
 @cindex intersection of sequences
-  This function returns a list of the elements that appear both in
-@var{sequence1} and @var{sequence2}.  If the optional argument
-@var{function} is non-@code{nil}, it is a function of two arguments to
-use to compare elements instead of the default @code{equal}.
+  This function returns a copy of @var{sequence1} from which the
+elements that appear in @var{sequence2} where removed.  If the optional
+argument @var{function} is non-@code{nil}, it is a function of two
+arguments to use to compare elements instead of the default
+@code{equal}.
 
 @example
 @group
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
index 4713deea750..38aaeba7c9b 100644
--- a/lisp/emacs-lisp/seq.el
+++ b/lisp/emacs-lisp/seq.el
@@ -567,7 +567,7 @@ This does not modify SEQUENCE1 or SEQUENCE2."
 
 ;;;###autoload
 (cl-defgeneric seq-intersection (sequence1 sequence2 &optional testfn)
-  "Return a list of all the elements that appear in both SEQUENCE1 and SEQUENCE2.
+  "Return copy of SEQUENCE1 with elements that appear in SEQUENCE2 removed.
 \"Equality\" of elements is defined by the function TESTFN, which
 defaults to `equal'.
 This does not modify SEQUENCE1 or SEQUENCE2."