How do the riding experiences of the both children differ in The Summer of the Beautiful White Horse?

In the short story "The Summer of the Beautiful White Horse" by William Saroyan, nine-year-old Aram, the narrator, discovers that his cousin Mourad has stolen a magnificent white horse. Mourad takes him for a ride, and then each of the boys rides the horse solo.
Aram explains that Mourad is thought to be crazy by everyone in the family except him, although the specific motivation for this is not clarified, except that Mourad loves to sing loudly, has a way with animals, and "enjoyed being alive, more than anyone else who had ever fallen into the world by mistake." Aram justifies the fact the Mourad has stolen the horse by considering that at least he had not sold it.
The boys take the horse out of town and into the fields, and for a time they let it run with both of them on it. Mourad has Aram get down, and when he takes off alone on the horse, he is in full control.

The horse stood on its hind legs, snorted, and burst into a fury of speed that was the loveliest thing I had ever seen.

When Aram climbs up onto the horse for his solo ride, however, he does not have the ease and control that Mourad has.

Instead of running across the field to the irrigation ditch the horse ran down the road to the vineyard of Dikran Halabian where it began to leap over vines. The horse leaped over seven vines before I fell. Then it continued running.

So we see that the riding experiences of the two children differ greatly. Mourad, who has a way with horses, rides with ease and grace. Aram, on the other hand, has little control over the animal and gets thrown every time he tries to ride. Aram does not learn to ride before the boys feel compelled to return the horse to its rightful owner.