“The SAT and the ACT are fundamentally the same. They are both internationally administered standardized test for HS students that primarily test basic reading and math skills in ways that differ from those used by ‘normal’ classroom tests. In fact, most of the questions that appear on either could also appear on the other one, because most of the rules on the two tests allow the same types of questions in many situations. There are exceptions to this, of course – each test also has question types that don’t ever appear on the other test. But the principles underlying the design of individual questions on both tests are still largely similar.” – Mike Barrett, author of: The ACT Prep Black Book.
The old SAT was called a “reasoning test” and the math level for example was at the middle school level but it was super tricky. The new SAT (since March 2016) is more “curriculum based” which means it is more based on what you have learned in your HS math classes. So you need to know your algebra 2 concepts, like your linear and quadratics functions, exponential and logarithmic functions etc. You therefore do need to review all the algebra concepts you learned and you will see them there. There appears to be less geometry than on the old test but still maybe 20% of the test is geometry.
The English on the SAT is definitely based on HS English curriculum concepts. The essay required well developed thoughts.
The new SAT, while it still has some tricky questions, is now more like the ACT, which has always been curriculum based, However the ACT has a science reasoning component which many students (even those in AP science classes) feel brings down their average. Being prepared and familiar with what the science tests of course will of course help!