The main difference between OEM and aftermarket taillights is their look. They are both manufactured to exacting standards and most are made to be D.O.T. and S.A.E. compliant. The big difference is with factory taillights your ride looks the same as all the others on the road whereas aftermarket one's help you stand out from the crowd. The next time you pull up to a red light while driving at night, have a look at the sea of generic "red" lenses around you and you'll see what we mean.