in chapter ten, how has the farm grown after several more years?

The changes to the farm are immense. The windmill is finished, but it is used for grinding corn rather than electricity. They're in the middle of building another for electricity. The pigs have changes too, they now all walk on two legs which causes a furor amongst the other animals, but only the sheep press their luck because Napoleon carries a whip is his now "free" hands. In fact, all of the pigs begin to carry whips as well as wear clothing; they even go so far as to socialize and deal with neighboring farmers. The pigs eventually reach the point where they've become so "human" that the animals can't tell them apart from their true human counterparts.

They look through the windows to see the pigs and farmers seated around the living room table, playing cards, making speeches and congratulating one another. Mr Pilkington makes a speech telling the pigs how impressed he is with Animal Farm, especially with the hard work and poor rations of the farm animals. Napoleon makes a speech in return, expressing his happiness that the mistrust between Animal Farm and the others is now at an end. He furthermore announces that the animals will cease to address each other as “Comrade,” and that “Animal Farm” will now revert to being called “Manor Farm.” As Napoleon finishes his speech to great applause, the animals outside seem to notice something changing in the features of the pigs, but what?

As the applause dies down and the card game is resumed, the animals creep away from the window. However, they hurry back when they hear a furious argument break out. The argument is because Mr. Pilkington and Napoleon have both played an Ace of Spades at the same time. But as the animals look from Napoleon to Pilkington, from man to pig and from pig back to man, they find that they are unable to tell the difference.

source for last paragraph above