Image Quality Comparison
Below are three sets of in-game screenshots that compare the low, medium, high, ultra and maximum quality settings. Click the pictures for a full-res 2560x1600 image.
The low and medium quality settings are very similar. There is slightly more detail when using the medium quality settings and the textures are improved. Oddly, the high quality preset looks much better than the ultra quality in our opinion. High offers more details overall, while ultra has softer shadows and lighting.
Unlike the previous set of pictures, there is a significant difference between low and medium here. The foliage off in the distance is softer when using the medium quality preset and there are small 3D rocks on the ground. Shifting from medium to high significantly improves texture quality and adds considerably more detail, such as the large rocks in the distance and the crisper textures.
Again, when going from high to ultra the overall image quality seems to be reduced, especially when comparing textures. Ultra only seems to improve the shadow quality while adding a few shrubs and rocks, while maximum offers a noticeable boost in detail. There's foliage on the distant mountain, while the mountains themselves have sharper, more detailed peaks. Shadows are also improved.
Skyrim's water quality was very similar when comparing the low and medium quality settings. Likewise, while there is a noticeable difference when shifting from medium to high, it's not drastic. Yet again, ultra seems to be a downgrade as it sacrifices texture quality for softer shadows and more foliage. Maximum restores the higher quality textures and improves most other visuals as well.