I am almost certain that the "W" means Windows keys. My black case is still an AT101W.
My guess is that someone has swapped case parts and internals.
The dye-subs are rare and found on the early ones, some people say the ones with Alps boards rather than Silitek. Personally, I have bought even old-logo AT101s that had ABS, and new-logos that had PBT dye-sub (only one, unfortunately). It is really a crap-shoot.
The good old cases have a metal bar in the back, which surely has no purpose other than to add weight (a few hundred grams at most) and you can install the bar in a newer case with a little Dremel work on the mounting post.
My "primo" AT101W has orange Alps from an AEK transplanted into an AT101W PCB mounted in a black case (with the post shaved and the weight bar added, along with waffle drawer liner padding), and the PBT dye-sub caps in pearl/pebble.
It is a Frankenstein to be sure, but it looks, sounds, and feels great. Too bad that the entire bottom row has to be ABS, but as far as I know the modifiers all changed to squeeze in the Windows keys (and whatever that other weird one that I never use is).