Welcome to posting on FlyerTalk, equinzo.

It varies by hotel, but the MVP rate is usually cancellable, while the lowest Member Discount rate is usually only advance purchase. So I don't see them as comparable, even if they did happen to be the exact same cost, but at many hotels I find (through "see more rates") that the MVP rate is even lower than all the other possible rates (Member Discount advance purchase, AAA cancellable, etc).

Not all hotels seem to offer MVP rates. And I don't know if all hotels that do offer MVP rates give the same discount for MVP rates. I just know that for the past couple months I've been consistently checking "see more rates" whenever I'm booking MVP (I did it sporadically before that), and so far everything under "see more rates" is more expensive, while the least expensive "see more rates" or two are typically advance purchase while MVP is cancellable.