Both the guns have different objectives. After world war 2 a US study concluded that effective range where a soldier can aim and shoot in war is 200 meters , AK47 has a larger bullet and thus more range and also recoil and thus less stable to handle. in AK56 the size of bore was reduced limiting to the effective range and with less recoil it is easier to handle. Terrorists prefer Ak47 as it has longer range and thier intention is not to aim and kill but to spray bullets on a large crowd causing maximum damage.
