Is there a way for me to rsync two directories comparing only filenames (and not file size, date modified, or any other criteria)?
rsync(1) man page:
--ignore-existing skip updating files that exist on receiver
--ignore-times option should do that.
Normally rsync will skip any files that are already the same size and have the same modification timestamp. This option turns off this “quick check” behavior, causing all files to be updated.