It depends. You might have done well on one test and not on the other. That is the case for me I think. I only omitted three or so on the SAT II, and got a 770 on it, but on the AP I didn't really pace myself so I had to leave 18 blank plus I thought the AP was more difficult.
You can't compare the AP with the SAT II because the SAT II is solely multiple choice whilst the AP includes a free response section. To begin with if you could compare them, then why would collegeboard have both the AP and the SAT II system? They might as well do away with one and stick to the other.
I think even the multiple choice themselves were completely different. I felt the SAT II was much easier in that if you had a basic idea of what a term or reference was, chances are you were about to figure out the answer because often the other choices had NOTHING to do with it. I thought the AP was trickier and tested your knowledge more.
I ended up with a 730 on the SAT II, don't know about the AP...