Honestly, there does not appear to be much difference between the two. You are aware of the dust cover, forward assist, and the lack of sights on the OR. The main difference is the barrel.

The Sport comes with a melonite treated 1:8 twist, 5r rifling barrel. The OR comes with a chrome lined 1:9 twist, standard rifling. Both barrels are the same grade of steel.

Sport trigger guard is forged as part of the lower and enlarged, where the OR has the standard trigger guard with the replaceable guard plate. The Sport handguards also do not have a heat shield, but most change these anyway.

When I was looking, I could get the OR at about the same price as the Sport at the gun show. I chose the Sport because of the rifling in the barrel. I felt like the Sport probably has the better barrel between the two for my intended use, but some may disagree.