There is an actual difference between All Wheel Drive and 4WD. All wheel drive had couplings that allow for differences in speed when driving and turning. 4wheel is a more locked system, where all of the wheels turn the same speed all the time. This is why they dont reccomend use of 4 wheel drive on the roads for extended periods of time. It leads to twisted axle shafts and broken CV joints. I guess the best way to sum it up is 4Wheel=two posis All Wheel=2 limited Slips.