The foliage off in the distance is softer when using the medium quality preset and there are small 3D rocks on the ground. Unlike the previous set of pictures, there is a significant difference between low and medium here. High offers more details overall, while ultra has softer shadows and lighting. Oddly, the high quality preset looks much better than the ultra quality in our opinion.
There is slightly more detail when using the medium quality settings and the textures are improved. The low and medium quality settings are very similar.
Click the pictures for a full-res 2560x1600 image. Below are three sets of in-game screenshots that compare the low, medium, high, ultra and maximum quality settings.