What's the difference between a comment in the archive and the bin?

When you delete a comment, it's moved to the bin. Deleting can't be reversed, so comments that are deleted will also be deleted on Facebook or Instagram and can't be recovered.

When you archive a comment, it's moved to the archive. Archiving doesn't change anything to the status on Facebook or Instagram but just moves the comment away from your inbox. You can move it back from your archive to your inbox, by clicking the "Unarchive" button.