It's possible that nvidia makes this difference intentional as some sort of weird product differentiation strategy. As reported, with a GeForce you are very likely to observe the following effects:
1. Textures look lower resolution because of applied texture compression;
2. Some parts of trees and bushes like branches and foliage are cut off the scene;
3. Distant objects look washed out, loss of detail in distance
4. Colours look washed out, applied very thin white colour filter on the images;
5. Fonts look with irregular shape, sharp curves instead of smooth curves, thicker letters, sometimes lighter black on the fonts
6. Contrast balance is broken