UX302 is 1920x1080 with 6GB RAM. UX301 is the one with the 2560x1440 screen. It's a weird pair; they gave the discrete GPU to the one with the lower res screen.
Presumably they're assuming most people going for a 2560x1440 screen are buying it for productivity software / readability where most of the software does not need all that much graphics performance.
Assuming the 5100 can handle 2560x1440, I'm guessing it's so benchmarks show higher FPS averages due to the lower resolution.