The pigs, by the end of the book, have become identical to the humans they replaced, bringing to mind the rock group Who's lyric, "meet the new boss, same as the old boss."
When the revolution begins, however, the animals are determined to live differently from their ousted human masters. To ensure they hold to their values, they devise the Seven Commandments of Animalism. These are as follows:
Whatever goes upon two legs is an enemy. Whatever goes upon four legs, or has wings, is a friend. No animal shall wear clothes. No animal shall sleep in a bed. No animal shall drink alcohol. No animal shall kill any other animal. All animals are equal.
By the end of the book, the pigs have violated all of these commandments: they walk on two legs, wear clothes, sleep in beds, drink alcohol, and kill other animals. They definitely have put themselves into a privileged caste, so all animals are no longer equal. They don't treat the other animals as friends. In fact, they work them more ruthlessly than ever, forcing them to toil for long hours, and give them ever less to eat. They even sell poor old Boxer to the glue factory when he can't work anymore, although the animals had originally been promised a beautiful retirement. They betray other, weaker, more good-hearted animals in every possible way.
Finally, to get away with this, they change the original Seven Commandments to two: "All animals are equal but some are more equal than other" and "Four legs good, two legs better!"
From lies to exploitation, the pigs abuse their leadership role. It's up to the reader to judge whether this is simply a story or if the same kinds of abuses go on today.
The pigs are exploiting the other animals efforts for their own personal gain. The other animals are working 60 ours a week to build the windmill, and carry out other back-breaking labor, while all the pigs do is give orders.
The pigs are also selling much needed food for their own profit, even though rations are getting scarce. To quiet any questioning of this practice, the pigs use the intimidation of growling dogs to ward off protests.
The pigs also move into the farmhouse and sleep in beds, while the other animals must sleep outside in the barn in their stalls.