Super Mario Bros 2 is very different than all the other Super Mario Bros games for the NES and for a very good reason. The game was never supposed to be a Mario game at all! In Japan, it was Doki Doki Panic but for some reason they released it in the USA as Super Mario 2 and the rest is history. You can choose between 4 characters: Mario, Luigi, Toad, and Princess. Mario is the all around average character. Luigi is kind of weak at picking up items/enemies but can jump the highest. Toad is super strong at picking up items/enemies but isn't a good jumper. Lastly, you have Princess. As you'd expect, she is the weakest at throwing but has crazy good jumping skills and hang time to make up for it. She can pretty much fly for like 2-3 seconds per jump which is very useful. Certain levels will be easier to complete with certain characters.