Those familiar with work animals would have no difficulty answering the question in our title, but most of us would have a hard time telling them apart. So let's study them a little.
Take the mule, for instance. This animal has a donkey for a father and a horse for a mother. Except in rare instances, a mule cannot be a father or a mother—a donkey and horse are almost always the parents of a mule. But when we reverse the parents—the father is a horse and the mother is a donkey—then the little one is called a hinny, although it looks just about the same as the mule. Kind of confusing, isn't it?
The Bible mentions mules many times. Even kings rode on them and people gave them as gifts to Solomon. They are about the size of an average horse, but have larger heads, much longer ears, tufted tails and smaller hooves. They are more surefooted and work more slowly than horses. In fact, they are very stubborn and can't be hurried.
Mules are common throughout the world, especially in Asia and parts of Europe, starting with light work when they are three years old and handling heavier burdens two years later. They make excellent pack animals over mountain trails. Thousands were used by the United States Army before modern machinery was developed.
How about the ass, which is also mentioned in the Bible? The names "ass" and "donkey" are given to the same animal; the male is also called a "jackass" and the female a "jenny." Although they have bigger ears they are smaller than most horses.
In the Far East, the ass still takes the place of a horse and is preferred by men and women riders. They are also used as pack and work animals. Jesus rode on one, as told in Zech. 9:99Rejoice greatly, O daughter of Zion; shout, O daughter of Jerusalem: behold, thy King cometh unto thee: he is just, and having salvation; lowly, and riding upon an ass, and upon a colt the foal of an ass. (Zechariah 9:9), "Behold, thy king cometh unto thee: He is just, and having salvation; lowly, and riding upon an ass." You can read the interesting story of this in the first nine verses of Matt. 21.
With few exceptions, asses (donkeys) and mules are stubborn and want to do things their own way. Because of this and the frequent need to use a whip with them, as well as with some horses, we are counseled in the opening Bible verse not to be like them.
Instead, another Bible verse says, "With good will doing service, as to the Lord, and not to men: knowing that whatsoever good thing any man doeth, the same shall he receive of the Lord." Eph. 6:7,87With good will doing service, as to the Lord, and not to men: 8Knowing that whatsoever good thing any man doeth, the same shall he receive of the Lord, whether he be bond or free. (Ephesians 6:7‑8). Another Bible verse says, "Serve the Lord with gladness: come before His presence with singing. Know ye that the Lord He is God: it is He that hath made us, and not we ourselves." Psa. 100:2,32Serve the Lord with gladness: come before his presence with singing. 3Know ye that the Lord he is God: it is he that hath made us, and not we ourselves; we are his people, and the sheep of his pasture. (Psalm 100:2‑3).
When we walk before the Lord as stated in these verses, we need no whip nor bridle and will find how much He loves to bless us.