WD are notoriously bad at distinguishing different models but the AAKS definitely exists as a) a separate product line and b) in 500Gb
The only thing stopping me taking the drive back, is that thats on the american WD site, and the AAKS is the only 500gb drive listed, theres is no KS.
also, looking at the popular online retailers, no one seems to sell both models, its either one or the other, and the prices are all simmilar, so im a bit stumped there....I mean I would take the drive back on principal as I detest being mis-sold things by shifty salesmen, but I need to find a reliable bit of info showing the difference