Sometimes artistic students do better on the ACT. The SAT was designed as an aptitude test. It tests your reasoning and verbal abilities, not what you’ve learned in school. In fact, the SAT was supposed to be a test that one could not study for (studying does not change one’s aptitude). The ACT, on the other hand, is an achievement test. It is meant to test what you have learned in school. However, this distinction between “aptitude” and “achievement” is dubious. There is concrete evidence showing that you can study for the SAT, and as the tests have evolved, they have come to look more and more like each other. (sourced from about.com)