One of the best ways to tell the difference between a donkey and a horse is by looking at the ears. Donkeys have really big ears while horse ears are smaller. For thousands of years, donkeys have been kept and used by people for a lot of things. But unlike horses, donkeys have their own minds and often prefer to do what is best for the donkey. Sometimes this is not what the human wants, and so there is often a standoff, and this sound of protest is heard.