For your species, thoughts to make then equine but not wme 1. Cloven hooves and/or side spurs / 5th toe type like Eohippus or Merichippus(sp) (First horses) wme have solid horse hooves. 2. Kudo hornns, not 1, but 2 swirled long horns. 3. A spike or spines of some sort perhaps on their shoulder blade area/withers which would prevent them from being used as riding animals. Pack animals perhaps but not riding animals.
Just a few random thoughts that would make them different.
I'll get back to the horse this next weekend. I'll be on a family vacation and should have some private time to use one of my daughter's laptops to do art on.
Equid