Question

What is main difference between the SAT-I and SAT-II?

Answer 1

The SAT I is the standard SAT test format, which you will need to take for most college applications. The SAT II tests are subject-specific tests that might or might not be required, depending on where you plan to apply.

Answer 2

Originally, the SAT I was meant to test aptitude and the SAT II was meant to test achievement. That is to say, one tested what you were capable of and the other tested what you knew. But when the College Board moved away from the idea that the SAT I tests innate ability, they framed it as a reasoning test, making the difference between the two less defined.

With the latest changes, the SAT I (now just the SAT) is more focused than ever testing knowledge rather than logic. At this point, I would say that the SAT tests general knowledge and and the Subject Tests assess topical knowledge.