Mules are slightly smaller than their horse parent, and when they grow they share traits of both a donkey (the long ears), and the horse (color, tail, etc.). A Mule in the grass.
For example, a 2014 Ford F-150 is considered a half ton truck but most variants can carry a lot more than 1,000 pounds in the bed. Since these terms are probably not going away any time soon, it's best just to think of them as smaller, mediumest, and more than medium.. (Pause for laughter).
Back in the day, a one-ton truck had the ability to carry 2,000 pounds of cargo, a three-quarter ton truck could carry 1,500 pounds, and so on. Pickups today far exceed these primitive weight classifications. The 2015 Ram 3500, for example, offers an impressive 7,390 pounds of payload.