So I had downloaded Mega Man Collection on 3DS when it was on sale and noticed you can change between Mega Man and Rock Man in the settings of each game. I know in the 90's because of rentals being such a big thing in the U.S. they made the American versions of certain Mega Man games a little different and more difficult to prevent beating it and returning in a single sitting. Is there a difference between changing this in the Legacy Collection version of the game or is it just superficial?

Turn on rock man version and start up megaman 1, you'll notice the differences immediately.