How would you describe the power structure in AF?

The power structure starts out as Farmer Jones (human/supreme dictator) and all the animals as slaves or proletariate. After Jones is run off, Napoleon the pig simply takes his place. Then there is a hierarchy of four legged animals all the way down to the two legged animals. Animals who could do a lot of work like Boxer were respected but still the pawns of Napoleon the dictator. Pigs were favoured among all the animals as the brains behind the whole operation.