there isn't really a functional difference between them, but there is a compatibility difference. You have to use a booster from a non-abs car if you're using a non-abs MC, or an abs one with an abs one. It doesn't really matter which you use, as long as the booster and MC match.

As for telling whether your booster is shot, I don't think theres really a test for it other than putting in a new one and seeing if it solves the problem... While you have it out (if you still have your original one sitting around) check the pushrod length on both and make sure its the same length too, that might be the cause of your issue.

And yes, the pedal should feel harder when you swap, but not extremely so.