The AK-47/AKM series has either no muzzle break on the original milled receiver AK47 or a small slanted muzzle break on the AKM, the AK-74 has a longer compensator style muzzle device. (different from the "trumpet" on the AKS-74U here) The gas block on the AK-47 is at a 45 degree angle, the AK74 has a right-angle. The wooden AK-74 stock has a groove cut into it. The AK-74 magazines are generally made from orange Bakelite plastic (or other colors if they're newer) and are less curved than AK-47 magazines.