The original Yamaha AWM, designed AFAIK in 1987, was a PCM sampling engine (Pulse Code Modulation) with an advantage for piano sounds: it used a filter that changed slightly the "color" of the sound depending on the force (velocity) the note is stroked.
As PianoWorksATL noted, at the beginning it only used one sampled layer, and today there are still Yamaha instruments that only use 1 layer with that coloring filter (I guess the P35 is one of them).
It has been many variations on AWM. The original AWM was mono, they added stereo samples a time after. During a brief time existed AWM-2.
Another thing we must have in account is that not every AWM engine is based on CF pianos: there are many AWM models that got the samples from the smaller S6 piano. That, in my humble opinion, could be the origin of the distinction between plain AWM and Pure CF (although this doesn't exclude the possibility that some AWM models use CF samples).
The last step of AWM has been RGE (Real Grand Expression). It promises many things that Roland's SuperNatural already does: natural decays, transitions between layers and so. In the opinion of many forum members this isn't completely true as they say RGE is almost identical to AWM. I don't even know if it has 88 keys sampling. I tried it but not at that detail level