As nouns the difference between stags and diff
is that
stags is while
diff is (slang).
As a verb diff is
(computing) to run a diff program on (files or items) so as to produce a description of the differences between them, as for a patch file.
As a proper noun diff is
(computing) a program, historically part of the unix operating system, which compares two files or sets of files and outputs a description of the differences between them.