What do allegories and fables have in common

A fable is an allegory that uses an imaginative illustration of events that have hidden messages brought by animal characters. It has either a moral or a political lesson that can be unlocked using analyzation. The animals are used as symbols to portray or associate with people. 

One clear example is the Animal Farm written by George Orwell, published last August 17, 1945. It was a political representation of the 1917 Russian Revolution.