Both Thompson’s and Grant’s gazelles possess white colouring on the hindquarters, but Grant’s gazelles have more white than Thompson’s gazelles, and Grant’s is paler and has bigger horns than Thompson’s. The young are more darkly coloured than adults. Males are larger than females and have longer, thicker horns, ranging from 50 to 80 cm.

Grant’s gazelles are sometimes confused with Thomson’s. However, Thomson’s is distinguished from Grant’s by its smaller size and the white patch on its rump. On Grant’s gazelles, the patch always extends above the tail.