Horses are tamable mobs that have five in-game variants: horses, donkeys, mules, zombie horses, and skeleton horses. The variants can appear in one of several different coat colors that exhibit different markings.
Horses: have a stocky build, can have 1 of 7 base colors: white, buckskin, dark bay, bay, black, dapple gray, and flaxen chestnut; and 1 of 5 marking patterns: no markings, stockings and blaze, snowflake appaloosa, paint and sooty. In total, there are 35 possible horse coat combinations.
Donkeys: smaller all around than the normal horses and sport long ears. Their manes do not protrude, but rather are drawn directly on the back of their heads and necks. All donkeys have gray-brown coats with darker ankles, ears, manes, and tails. Donkeys cannot be equipped with horse armor, but can be equipped with chests to store up to 15 stacks of items.
Mules:the offspring of interbred horses and donkeys, and are closer to (but not quite) the size of a normal Horse. Their ears, coats, and manes are like those of a donkey, though mules’ coats are darker and reddish-brown. Like donkeys, mules cannot be equipped with armor, but can be equipped with chests.
Zombie Horses: appear to be the horse counterpart of zombies. Like zombies, zombie horses are green-skinned, and their eyes are completely black.
Skeleton Horses: appear to be the horse counterpart of skeletons
Video time again!!!! As usual, here is the link to the Wiki website. Also, below are two videos about horses: