This is an old post, but I will point it out anyway:
The displays are Samsung manufactured.
Samsung is the only company with OLED at this pixel density.
The last time that Samsung fundamentally altered their OLED fab (the shift from 720p to 1080p), they initiall encountered yield and/or output problems that prevented fullscale implementation of the new display resolution node in its first generation of devices....
more simply put, Samsung expected that they would not be able to make as many working 1440p displays at the speed that they managed to achieve this time around, because they last time they switched to a higher resolution they could not meet their own handset demand and they had to ship a bunch of Galaxy S phonse with 1080p LCD displays.
This time they met, and greatly exceeded, their own internal demand and sold Motorola the excess capacity.
Motorola has their own proprietary circuit board, display firmware, etc. and the AMOLED vs SAMOLED is really the equivalent of saying that Motorola has either used an off the shelf, license-free or cheap, backplane construction that does not have its own marketing language.