The only thing that was different was that they didn't get captured as slaves the same way they did in the book. They didn't follow the blue star in the book. Eustace didn't sit on the mast in the book because he was a dragon and he didn't write 'I am Eustace' in lava letters. In the book they asked him was he Eustace and he nodded his head. He still could understand them even though he was a dragon. Aslan didn't change him back the same way he did in the book. In the book he took Eustace down to a well and then he told Eustace to take off his clothes, which means his skin. So he scratched his skin off and then he found some more skin, the same kind so Aslan made a deep scratch into all of Eustace's dragon skin and then he was a boy again.