Sometimes a hold, at least with the UCs, means that they're waiting to send you an interview invite or secondary. That's the only time I think there's a difference. After you've interviewed and you haven't been rejected or accepted...you're on a waitlist and being held.
I got the same HOLD from CWRU (kinda bummed because I interviewed so well and they were so complementary towards me). I think another school explained to me what it meant. A HOLD means that in every session that the ADCOM meets to discuss the recent interviewed candidates....they also discuss the HOLD people and amongst all of them..... send out acceptances.
I think a wait-list is more of a thing where you are ranked somewhere on it and wait until that many people before you withdraw. Then you will be accepted. Usually, wait-list start in April or May.