Mario runs faster, and Luigi jumps higher. Also, if Luigi hits a 20 coin block 10 coins spill out instead of Mario where they come out one at a time (with Chocolate Island 2 as an exception). If Mario rides a Yoshi then anything Yoshi eats that isn't a key, a shell, or a spring gets swallowed instantly, but if Luigi rides Yoshi then yoshi waits a couple seconds, so Yoshi can spit the enemy out, or just wait to swallow it. Also, if Luigi rides Yoshi his jump is just like Mario's. I would say Mario is better, but Luigi is good on Yoshi. The exits unlocked for each bro are Mario 94, and Luigi 2.

quote rezzy234

The exits unlocked for each bro are Mario 94, and Luigi 2.

Sorry. I meant on my copy of the game.