What is the difference between Ultra and High settings?
Ultra is better. Better textures. I recommend playing on low though if you play survivor.
Do you have a better technical answer than that? Like the specifics.
Textures depend more on your resolution. If you set your resolution at 100%, then the textures will look nice.
The graphic settings are responsible for animations, environmental effects etc. If you set it at Ultra, then the animations will look nice and realistic, as well as the effects.
If you want a good texture quality, then set your resolution at 100%.
If you want beautiful and realistic environmental effects and animations, then set your graphic settings at Ultra (I don't recommend doing so if you don't have a good PC cuz it will most likely be laggy). That's why I suggest playing on high if you don't have a good PC.