They are both members of the deer family. Both elk and deer males have antlers that grow and break off each year. Both are herbivores and have the same predators. The gestation periods for both are around eight and half months. Although they are alike in many ways, there are also differences.
Elk are larger than deer.
Deer are a lot faster than elk and can leap much higher. Elk are browsers and deer are roamers. Elk tolerate extreme temperatures better than deer. The skull on the left is that of an elk.