Only difference I saw between the two was one came in 20 round green boxes and the other was approx 125 rounds wrapped in paper in spam cans(4 of these per can). Any steel cased ammo will be harder on extractors and such over brass cased. Personally, my Dad, Brother and I have shot a bunch of this ammo in our rifles and it seems good. It chronographs on the higher end of NATO spec velocity while the Czech surplus we have is on the lower end. The Norc IIRC, is about 2700-2750fps while the Czech is between 2600-2650 fps. Our rifles seems to shoot it quite accurately, YMMV of course, but we are averaging around 2-2.5 inches at 100 yards.
Also both the Norc and the Czech ammo is berdan primed so we treat it as corrosive, just in case.