In a Nutshell
Antelope and deer appear very similar in appearance, and are thus often confused by nature enthusiasts, hunters or photographers. In fact, they are far more different genetically than you might expect. Deer are cervids, in a family of their own, while antelope are closely related to sheep and goats.
The Whole Bushel
The deer family (Cervidae) comprise a fairly uniform subgroup (family) of Ungulates, which is the order including all cloven hoofed animals. Most of the 47 cervids have a fairly typical deer-like appearance, while dwarf deer and moose tip the two ends of the deer size spectrums.
Antelopes, however, form a far more diverse family of ungulates that are far removed from deer in taxonomic status. In fact, these animals are much more closely related to cows, sheep and goats than deer, and fall under the family Bovidae. These are basically the cow-like animals, comprising 145 incredibly diverse grazing species.
In keeping with this true genetic relationship, antelope may resemble cows much more than deer. The Wildebeest, for example, is actually an antelope. Antelope only inhabit the Old World, and occur primarily in Africa. Deer have a global distribution apart from Australia and Antarctica. North America’s Pronghorn Antelope is not an antelope at all, but a natural oddity in its own family.