North America hunting
The deer most sought after in North America, east of the Rocky Mountains, is the white-tailed deer. West of the Rockies, the mule deer is the dominant deer species. The most notable differences between the two, other than distribution, are the differences in ears, tail, antler shape(the way they each fork), and body size.
Whitetail Male Deer at night in Central Texas
The mule deer's ears are proportionally longer than the ears of a white-tailed deer, and resemble that of a mule. Mule deer have a black-tipped tail which is proportionally smaller than that of the white-tailed deer. Buck deer of both species sprout antlers; the antlers of the mule deer branch and rebranch forming a series of Y shapes, while white-tailed bucks have one main beam with several tines sprouting from it. White-tailed bucks are usually smaller than mule deer bucks. Both of the species lose their antlers in the winter time.
Moose and elk are also popular game animals that are technically species of deer. However, hunting them is not usually referred to as deer hunting, it is called big game hunting. They are considerably larger than mule deer or white-tailed deer, which makes hunting them rather different
edit: Leave the solicitations out of the posts or your user will be removed.