Differences between Percy Jackson and the Lightning Thief- Book and Movie

These are the differences I've spotted:

Age:Percy is 12 in the book but looks like 18 in the movie.

Percy uses an iPod touch to see medusa's reflection in the movie but he uses an orb to see medusa's reflection in the book.

Sally was left behind in the underworld in the book but she was not in the movie.

Medusa is old in the book but young in the movie.

Percy does not have iPod touch in the book but he has an iPod touch in the movie.

Annebeth is described differently in the book and in the movie.

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I prefer the movie to the book as the movie makes the story more realistic. I feel that the book and move should be the same, without any differences. The scene which I liked most is the scene where Percy and his friends fight the multi-headed dragon. The dragon looked really realistic and I felt that the movie can be improved greatly if it is 3D like Avatar.All in all, I enjoyed the movie very much and I hope I would be able to watch it again.