This nice specimen was seen near Flomot in Motley Co. Texas. Mule deer are so named because of the length and size of their ears. Odocoileus hemionus is different from the White-tailed deer in terms of their ears, their antlers, and their tail markings.
As the mule deer antlers form they split in to y shapes as they grow. Each branch of the Y can subdivide to produce more branches. This deer has had 2 subdivisions before reaching the terminal tines. On White-tailed deer, their tines branch as offshoots of the main branch of the antler and lack the splitting and resplitting of branches seen in mule deer.
The tip of the tail in the mule deer is black and is held down when fleeing. White-tailed deer lack this mark, and raise their white-flag when they flee.
Finally, well fed mule deer tend to be larger than white-tailed deer. The ranges of both species overlap in this part of Texas, and you can see both kinds of deer. Without antlers, ear size and tail color and tail display are the way to tell them apart.
Beware of approaching either kind of deer in the fall when the rut is occurring, males can and will attack people.