Independent of what marketing has decided to label: 4WD is four wheels receiving drive. AWD is all wheels, if one, then one, if three, then three, if 18, then 18 wheels get the drive. If a vehicle of four wheels receives drive to two wheels until traction loss and delivers drive to other wheels, it's 2WD. This is all ratio independent, but I'm just a schmuck.
Ah, I'm typing this and reading further -- Moppie is sensible. It _is_ marketing. I say stay critical and logical, forget the marketing, pulling marketing weasels more to our view. Observe what Audi has done in recent years to goof mainstream AWD Quattro.