The body lift lifts the body away from the frame. The "real" lift lifts the frame away from the axles. The body lift has limitation because some parts are mounted to the frame (engine) and other parts are mounted to the body (radiator), so you can only go so high before you need to do more mods. Also, the reason to do a lift is to get your truck up and away from rocks and other obstacles. The body lift only moves the body. The real lift will move everything except the axles. Depending upon the kind of real lift you do, you might get more axle articulation, which improves traction on uneven terrain.