Diffoscope is a diff utility which recursively unpacks archives, ISOs, etc., transforming a wide variety of files into human-readable forms before comparison instead of simply showing the raw difference in hexadecimal.
I recently added a progress bar when diffoscope is run on a terminal:
Note that as diffoscope can, at any point, encounter an archive or format that requires unpacking, the progress will always be approximate and may even appear to go "backwards".
This month sees us back in the Lord Darcy, which we have been to in the past. Anyone with something to show or talk about, please give advance notice on wylug-discuss on the meetups site< http://www.meetup.com/West-Yorkshire-Linux-users-group/ >or as a comment here. The time will be around 7:30 pm. Look for a bunch of us sitting round a laptop.