I couldnt find a good explanation with google. My friend explained it as basically a 4x4 is a 4 wheel drive system that senses slip and automatically puts the vehicle into 4 wheel drive when necessary. He says a 2x4 you are in 2 wheel drive until you push a button that puts you into 4 wheel drive. Is this accurate? Sounds like one is manual 4 wheel drive, the other is automatic 4 wheel drive. The naming convention is confusing to me if that's that's the case.