In the final chapter of Animal Farm, the pigs erase the last remnants of Animalism. The animals can hardly remember a time when they dreamed of heated stalls or retirement. Their lives are filled with endless work and hunger, work and hunger. The final straw is when the pigs reduce the Seven Commandments of Animalism to one:

ALL ANIMALS ARE EQUAL
BUT SOME ANIMALS ARE MORE EQUAL THAN OTHERS

After this, the pigs show up to the farm carrying whips, and nobody protests. They install a radio ("wireless") and a phone in the farmhouse where they now live. Napoleon shows up wearing human clothes, which was once forbidden, and "his favorite sow" wears one of Mrs. Jones's watered silk dresses.

When human farmers come to visit, they are impressed with how much work the pigs get out of the other animals. Napoleon gives a speech in which he disavows the farm's radical past and asserts they have the same conservative views as the other farmers. The animals no longer call each other comrade.

Finally, the pigs and the humans begin to play cards. As some of the other animals peep through the window and watch the players quarrel, they suddenly can't distinguish the pigs from the humans. The book ends on the quote above, in which the animals find it impossible to tell pigs from men.

The quote means that the pigs have so closely followed all human behavior that they have become indistinguishable from humans. They might call themselves pigs, but they no longer act like animals. All the dreams of equality and building a newer, better world in which animals would get ahead materially and have dignity have been erased. Farmer Jones might as well have never been overthrown.

This is a commentary on the way the ideals of communism were betrayed under Stalin, who set up a dictatorship in which a small class of Party members lived very well and the rest of the population did not. On a more universal level, it is a warning that ordinary people in society must not give up their power, or gradually, their rulers will repeat all the excesses of the past.

This quote is the last sentence of Orwell's novella Animal Farm, and illustrates how the pigs have become oppressive rulers, much like their previous human owner Mr. Jones. At the beginning of the novella, old Major inspires the animals to revolt against their human owner and gives them several significant tenets to follow, which the pigs develop into the Seven Commandments. The majority of the Seven Commandments warn the animals not to interact with any humans or imitate their habits. The tenets forbid the animals from sleeping in beds, wearing clothes, and drinking alcohol, while simultaneously promoting solidarity and equality among every animal.

Unfortunately, Napoleon successfully usurps power and begins to rule the farm like a tyrant. Under Napoleon's reign, pig's enjoy special privileges while the other animals toil throughout the day and live difficult lives. Gradually, Napoleon and the other pigs break every tenet and alter each of the commandments. In chapter 10, the pigs begin walking on two legs, carrying whips, and wearing clothes. They not only act like their previous cruel human owners but also look like them too.

One night, Napoleon invites Pilkington and some other farmers over to dinner as the animals watch their meeting through the farmhouse window. The party then begins playing a game of cards and chaos erupts after Napoleon discovers that Pilkington is cheating. During the melee, the animals cannot distinguish the difference between the humans and pigs.

The fact that the pigs cannot be identified from the humans reveals the extent of their corruption and demonstrates how revolutions do not always produce their desired results.

This quote comes at the end of Orwell's work.  In this setting, the animals have gathered around the farmhouse to watch the dining/ celebration between the humans and the animals.  As they heard Pilkington's toast and Napoleon's follow- up toast, the celebration and drinking revelry took the animals back to an extent.  Surveying the room of  and humans, the animals on the outside could not tell the difference between the beings on the inside.  This helps to bring out Orwell's fundamental point that politics and the constructs of power are universal, and that those in the position of power have only one primary concern and that is not losing it.  Both the humans and the pigs have found their common ground, which is being able to exploit their workers and become masters of their respective universes.  When the argument over the card game breaks out, the animals look again and see all of them inside, no different from one another.  The dynamic of "insider" and "outsider" has made those who have power, regardless of animal or human, those who are in control and those who do not have power on the outside looking in.  Orwell's main point is to draw the distinction here that "the twelve voices shouting" were not representative of the animals' interest, but rather in protecting their own share and their own hold on power.  There is no more of "animal vs. human" or "Animalism."  There is only power and those who have it are inside the farmhouse and those who don't are on the outside of it.