They will deny that you have a degree from them if asked. The difference it can make: When a future employer has degree requirements, the university will say "

They will deny that you have a degree from them if asked. The difference it can make: When a future employer has degree requirements, the university will say "no, he has no degree from here" when someone calls to check, closing off all sorts of jobs. If someone is doing a background check, the "claims a fancy degree but the school denies it" line is not going to look good. Etc. Sure the person still has the education, but they haven't got the right credentials in a verifiable way.