We noticed last year that USMLEasy was just a complilations of PRETEST questions.
I'm still reading about USMLEWORLD vs Kaplan for Step 2. Many mixed reviews, but everyone is saying the same thing:
Kaplan: more similar to actual exam. 60% is passing.
USMLEworld: harder, pickier, extented explanations. Your scores will be lower than Kaplan, but you shouldn't comapre the two scores. Some called it better to "study from."
Not an expert, just reading posts. I'm still reading by the way.