Are the College Board or Khan Academy practice tests for the SAT more accurate?

I seem to do a lot better (150-200 points higher) on College Board practice tests than the Khan Academy practice tests. Are the tests on Khan Academy harder than the actual SAT?

Both College Board and Khan websites contain the exact same 8 official College Board practice tests, 4 of which are actual prior administrations of the SAT (test #8 was administered in Jan 2017). I don’t know whether Khan has more practice tests than the official 8.

u could use prep books too, some are really good