"Grafton--You are correct 4WD = AWD."
That is a generalization, and not 100% correct. AWD has the ability to move the power from wheel to wheel, where 4WD does not have the ability. The AWD in a subaru uses a series of three viscous differientials to move the power between the wheels and allows a difference in speed between the wheels. This is why AWD can be driven on dry roads without destroying itself. Despite what the marketing says, AWD does not "send power from the wheels that slip to the wheels that grip." On many subaru's that have open front and rear differientials, the opposite tends to occure.
Later,
Seth E.