I checked it out and found that there were three that differed to some degree. The biggest difference is in the "brown" skin. Compare the mount texture applied to the wild model (left) with the existing wild horse texture (right):
The mount's coat is a much more standard brown, far less orange.
The other two cases are MUCH more subtle and I'll show them below. Again, mount skin (applied to the wild model) is on the left and the existing wild model skin is on the right:
In the latter two cases, the wild skin is just a little redder than the corresponding mount one.
These mount textures could very easily be used on the wild model if they were copied over, and would make great extra variants - especially the first one, which isn't like any other colour available. The other two would only offer subtle variations.