Most students perform better on one exam versus the other given the slightly different orientations of the tests. I typically advise my student-clients to try both after reviewing test strategies and questions from each. Then if one proves to be the stronger choice we emphasize that test in our work together.
These days most colleges will accept either test, since there is a widely used concordance chart that permits direct comparison of outcomes. The tests are more alike than not, but here are some of the key differences that may suggest a stronger performance on one of the exams:
Generally speaking, the SAT plays to students who read a lot (including reading for pleasure), and consequently have larger vocabularies. In my opinion, this is the most critical difference between the tests. The SAT automatically includes an essay-writing component, although with the ACT this is something that must be added to the test registration if desired. The majority of more highly selective colleges request the essay component, although many colleges are okay with the ACT without essay.
While the SAT is the longer test (at 200 minutes) when compared with the ACT w/out essay (175 minutes), the ACT has longer test sections, so students with attention-span issues may not do as well. The SAT rotates students through nine alternating test sections lasting 25, 20, and 10 minutes, while the ACT offers four sections lasting 45, 60, 35 and 35 minutes. Among the ACT segments is a science segment that requires students to interpret data charts and illustrations, so students who are into science this may do well in this area.
The ACT covers more advanced math problems with the inclusion of some trigonometry, although it is generally considered the broader test, relating more directly to courses taken in high school. The SAT is more esoteric, requiring more complex, critical thinking to answer many of the questions. This is seen in the essay components as well, with the ACT questions appearing to be more straightforward.
A lot of good info is available on the test websites, including local administration dates and sample tests and questions:
Pinnacle just concluded a 3-week ACT series and is about to launch a four to six-week SAT series for students in the Denver area testing on Nov 5 or Dec 3 For more information see the website: http://pinnaclecollegeplanning.com/tutoring/