The difference is it's a guaranteed two shot kill with high aim assist and RoF, it can still kill you after you outgun the thorn user, it leaves your shields down for 3 seconds longer than any other gun so it makes you vulnerable to the rest of his team and puts you at a huge disadvantage in peek-a-boo gunfights, and the green screen can be disorienting. Thorn just does too much for how good it's base stats are.