I had always heard that the SAT was a better for abstract thinkers and ACT better at testing knowledge. Not sure if that is true our school recommends students at least try a sample of both before deciding. My daughter took the ACT and I always assumed my son would do better on the SAT. (Not sure because of the upcoming changes.) But I have never had DS15 take either test yet. The SAT currently penalizes for guessing could that maybe have effected your sons score. Perhaps the problems he did get wrong lost him points?
When I was in school I often did poorer on test that I thought easy. I would get lazy and make more mistakes.
