I've never really thought about whether the game looks the same using its Windows vs Linux renderer. I installed HL2 to check out the anniversary update and decided to try the Windows renderer on Proton. Would you look at this difference... Linux is the top one, Windows is the bottom:
Is this is a thing? Have you tried other games and seen the Windows version looking better?
The exact same game. The only difference is whether I've chosen Force Compatibility > Proton 9 or not. I uninstall before switching compatibility and reinstall, because the Linux version doesn't come with the Windows binaries and vice versa.
I think beyond the binaries and therefore renderer used, there might indeed be differences in the assets. The posters are obviously different textures as you said.
I haven't looked in a while, but I thought the assets and binaries are separate, and it's possible to switch binaries.
Could be. I just went the safest route. Uninstall -> switch compatibility -> install.
The posters are rendered in a different order for some reason. In one, the combine posters are on top of the normal ones, and in the other, the normal ones are on top of the combine ones.
The combine ones should be on top as they are oppressing anything that could be seen as good, happy, or relaxing for the citizens.