well, i'm not an expert, but i believe that the SAT II's are subject mastery tests like the SAT's except they include science, world history, and a language, and not very many school require them. from what i've heard, the ACT's are just like the SAT's (many people have said it's easier) except some schools only look at those scores and some schools look at both O_o

the ACT is really similar to the SAT, exept there is science on the ACT and they do the english part and writing part a little differently. but it's pasically the same thing. some schools prefer one or the other, so i took both.