Hi albo94,
These two practice CAT results aren't as different from one another as you might think. GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Assuming a similar 'swing' in how your CATs function, these results show that your current 'level' is somewhere in the high-500s.
The scoring algorithm on the Official GMAT is far more complicated than most people realize. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. The most realistic CATs available are the 6 from GMAC (the 2 free CATs, and each of the 2 that come with Exam Pack 1 and Exam Pack 2). Since you just took a practice CAT, you should NOT take another one too soon. You should study as you see fit for another 1-2 weeks, then take a new FULL-LENGTH CAT (with the Essay and IR sections). Once you have those score results, you should post back here.
1) What is your goal score?
2) When are you planning to take the GMAT?
3) When are you planning to apply to Business School?
4) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich