Two things go into achieving 2200+ scores.
1- Be naturally intelligent. No one I know (myself included) got to the range you look for without being a naturally intelligent individual.
2- Practice. In addition to being intelligent, you need to understand the way in which questions are asked and the concepts included on the various sections. Intelligence will only get you so far. It's very rare for someone who scored 2300+ to have gotten there solely through being a genius. Of course it's not impossible, but for us mortals, practice is our best friend. I suggest Grubers for math, the Wall Street Journal and other scholarly publications for CR, and the Blue Book put out by the College Board for practice tests.
As for test difficulty differences, I don't really buy it. Just focus on getting the best score possible and you'll do fine.