@Senff – I don’t pretend to be an expert on the distinction. They’re buzzwords. (Kinda hard to be an expert on something you don’t care about.) This is the most succinct summary I’ve come across:
Where the two methods differ is in their delivery of the responsive/adaptive structures: RWD relying on flexible and fluid grids, and AWD relying on predefined screen sizes.
—Ryan Boudreaux, about halfway down under “Comparisons and Distinctions.”
I would tend to look at them both as attempts at solving the same problem, though I think AWD (according to this definition) falls short.