The are both transflective (for sunlight readability) memory-in-pixel (for power efficiency) LCDs. The black & white one is the same display as was used in the Pebble 2, and the color one is most likely the display which was planned to be used in the Pebble Time 2 (mostly comparable to the Pebble Time display but larger).

I agree that a true electrophoretic display is a lot nicer to look at; unfortunately the refresh rate leaves a lot to be desired in a highly interactive watch. Hopefully someday we get a technology with the best of both worlds.