Neither one is good for u....and just because u cant concentrate or do ur homework doesnt mean u have ADD, in most cases u just need to train urself to concentrate in class and force urself to do homework....try a few different things to help u out w/ ur skool problems...
Both increase heart rate a pretty good amount, put u on edge, and u become dependant on it and ur tolerance levels increase over time(so u then have to take a higher dose)....
Also to who asked about the ambien question....its a sleep medicine, very powerful medicine also...for the ppl i know who take it usually it takes on average about 15-20 min until ur out cold from it...awesome sleep aid but like any medication tht helps u sleep it has a tendancy to make u dependant on it.