difference between these two cams?

This is getting WAY too complicated. Cams (roller or otherwise) are much like carburetors. When in doubt, choose the smaller one, you will be MUCH happier with that instead of one that's too big. It really is that simple. But as I said before, I don't think you will ever know the difference. We can bat around lobe shape, opening and closing ramp rates, how big the flux capacitor is and on and on, but the question is a simple one and deserves a simple, non confusing answer.