The aardwolf is in the same family as the hyenas, however there are many differences between the two. For starters, the aardwolf has a more slender muzzle, sharper ears and a long mane down the midline of it's neck and back. But the easiest way to tell the difference, is to take a gander at it's feet.
Picture from Aardwolf Alpacas
In comparison to the hyena, the aardwolf is less of a runner, so the aardwolf's front feet have five toes each, unlike the four-toed hyena.