Emu's are the second largest birds in the world and the largest birds native to Australia. Ostrich is the largest bird in the world by height and a native of Africa. The emu have deep brown feathers and generally is very difficult to distinguish between the male and female of the species. However, during the mating season the emu hens grow black feathers on the head and the bare skin on the head turns blue. The male and female ostriches on the other hand have different colored feathers. The male ostriches have black feathers with white on the wings and tails while the females have grey brown feathers. The Emu has very strong legs with three toes which allow it to run at speed of upto 30 mph. The feet are said to be strong enough to kill a human. The Ostrich has extremely strong legs with two toes that are designed in a manner to enable it to run at speeds of upto 40 mph. The ostrich also have exceptionally large eyes in relation to their heads. In fact they are said to have the largest eyes among the land vertebrates.