That photo of the husky just pops more on your lg oled thanbthe Alienware - the Alienware continue to look full to me in any comparison- must be that awful anti glare coating
It popping more on the LG is going to be due to the white sub pixel. At higher brighness for white colous, it can really make highlights pop. But it washes out other colours when they are peaking.
The reflective coating also helps to improve clarity and luminance of a display compared to a matte coating. The matte coating diffuses the image a bit making it softer and also diffracts the light output more.