Not trying to start a flame war so all I want is facts, no hear-say or opinions.

What is the real difference between the R50 and the S50?
(i.e. better bearings, better head, better tail design, better power to weight)

I don't want to know which one is better for a beginer or an expert I just want a side by side heli comparison, I don't care about manuals either, just one fully built and setup heli next to the other with the same engine, radio, and servos. This is from the box, too... no upgrades.