There is a difference in the way that a lot of the AWD vehicles operate in AWD. The Explorer lets the computer decide when it should be in 4wd where other vehicles like a Subaru is actually in 4wd all to time, hence it is a AWD. Also a lot of those vehicles don't have a option like we do on the Explorer in putting it into different traction modes.
I can watch the traction control in my user information center and see when it is in 4wd and not. For most of my driving it is only in 2wd. Now if I accelerate quite heavy and watch it I'll see the rear wheels start to have power and then it will back off as I let off of the gas.