I always thought they were significantly harder than the AAMC tests. I scored on average a 32 on AAMC but only a 26 on TPR. However, I never put 100% into the practice tests on TPR. I gave abotu 80% to two TPR tests and got 28 and a 29. The others brought down my average. In my case, maybe a 3 point difference?
However, do the AAMC tests before the real thing and make sure you take the higher number tests since those are more like the real thing. Numbers 4 and 5 are ridiculously easy and you will think you will score higher than you actually will.