They're both the same thing, just like any game from machine to machine they have their own personality.
I will say on my MMR it's much easier (for me) to do EVERYTHING but castle shots. Usually on MM I'd get screwed by the damsel shot, and on MMR I can punish it. Plus a left lane joust orbit will come out and hit a raised right flipper and bounce right into the Catapult, where my MM just didn't seem to have that kind of flipper power.
MMR is on default btw. Game is level but it's steep... 8 or 9 degrees, outlanes wide.