Intent. One was designed for the military, the other for hunting. Remington ran out of crap to sell, so they decided to go after the AR platform in order to get guys to spend money. You must have fallen for it too. Funny, the AR goes all the way back to the early 60's and yet only today is it the be all end all of deer hunting rifles. There is no functional obsolescence (sorry for the big words) in firearms, so somebody had to create a new buzz. It started with the WSSM garbage, and now it's the AR world. Pick up a book or two and learn a little market analysis, sales analysis, and cost accounting and you'll see the picture. The demand is not from a need for a better way to shoot deer, it's from an obsolete industry. The problem is most Americans cant stand the fact that most of it is being shipped overseas. Hence the Miroku at the bottom.
Last time I checked, Remington had a semi automatic rifle. Damn, I thought I actually had one at one time. Must have been mistaken. I wonder why the long wait?

Guess I'll just head back to Idaho for some Elk hunting with a 50 BMG. Maybe I'll swing by Arizona on the way and have Mike Dillon fuel up the heli so we don't have to walk as much, I hear he's pretty accurate with the mini gun.