Unfortunately no one replied here. Since you must have already taken the test, how did you do?

Sorry for the super-late reply here. Hope you realized that since they are two different tests made by two different prep companies, it isn't unusual to score 50-100 pts different. Practice CATs are great for working on questions in a test-like environment for pacing and stamina-building, but I wouldn't put too much faith in the score they churn out at the end (not to pick on these companies specifically; I often recommend their materials, but I think this is true for ALL private CATs). Think of the score as a "ballpark." If you see your score improve over several tests with the SAME company, I think that's a good indication of improvement. However, Powerprep is the most reliable indicator of your actual GMAT score.