Psh, the PSAT is harder than the SAT, so don't worry.
The ACT is a test that most colleges accept in place of the SAT. And by most colleges, I mean practically 99% of them.
It has 5 sections (English, Math, Reading, Science, Essay) and is a bit shorter than the SAT and is soooo much nicer..
The ACT is out of 36, so it's kinda different. I would recommend that you try the SAT and the ACT because most people do a lot better on one of them, because they are set up so differently.