Both are US Keyboards, and both keyboards have lots of travel so both keyboards are great for typing
Lenovo is slightly heavier
Lenovo is bigger footprint for sure, the Alienware M16 R2 was redesigned last year and the back exhaust are was cut off to make it the same size as a tradition laptop so the its more portable (fits in a regular laptop sleeve)
I'm just really surpised how Alienware was able to fit a full gaming laptop in such a thin laptop without the back hump that other gaming laptops have such as G15/G16, Asus Strix, and of course the Legion