Donkeys are browsers. They nibble for a while on whatever is available, then nap, conserving their energy.
Horsesare grazers. They have a high metabolic rate and will graze 18 to 20 hours a day to maintain their body weight.
Donkeys and horses are both prey animals. However, donkeys are not like horses, mentally, physically, and most of all emotionally.
Donkeys are buddy animals and usually pair off in twos. They tend to develop strong emotional attachments, somewhat like a friendship, even if they are pastured with several other animals.
Horses are herd animals and prefer to be in a large group.
Donkeys are not easily startled. They have a keen sense of curiousity. They may run a short distance but then stop and turn to face whatever scared them before the make a decision whether to stand still or continue fleeing.
Nature provided horses with a strong flight instinct and long legs so they could run to escape predators. Horses easily startle. Horses run blind and will jump over and through any obstacle in their path.
Donkeys are more independent in their thinking. As a result, most horse training methods have only marginal success when used on donkeys. If you attempt to dominate the donkey, he will just avoid you. Donkeys think. and reason. The make decisions based on their safety. And they can learn what it is we would like for them to do if we take the time to explain it to them. The strongest instinct in a donkey is survival. Training a donkey relies on showing him by words and actions that he can trust you to protect him from harm.
A donkey is stronger than a horse of the same size. You can not muscle a donkey. You can not force him. He has to understand what it is you are asking him to do.
Most horse training methods rely on a horse's reaction to a pecking order in the herd. The horse trainer becomes the boss horse of the herd to teach a horse to react to a cue for a particular action.