Quality: Well obviously many of the parts that going into the AR are universal. But the difference bxn (between) Rock River Arms and other companies, is that RRA made the key components of the highest quality. These being the chamber, barrel and the trigger. My RRA came with a match barrel, match chamber and a match 2-stage trigger. The story as I understand it on how RRA came to be is that some top guys at Bushmaster and Colt got together, discussed what they disliked and put together their own AR series.
Barrel: I have heard (not proven) that the Bushmaster barrels are not as good, at least quality wise as compared to RRA. The RRA comes with a Wilson. I know people have shot them and done great with them, but again I think the RRA is a better quality barrel. The RRA also comes with a 1:8 twist, which I have come to respect. It can fire heavier bullets due to the increased twist rate.
Chamber: The RRA is chambered in .223 Wylde. I'm not sure on the exact differences here but i know the chamber is a national match.
Trigger: I love my trigger!!!!!!!! The national match 2-stage trigger that came on my RRA is awsome.
Price: My RRA was only $1000 bucks!!! This makes it very competitive,
especially when you look at the quality of the rifle.
I purchased mine with the EOP upper, which I think is a great idea. So there ya go westy I think thats about it for the rundown. Any more questions/disagreements let me know.