Book characters are characters are exclusively only from the original books and do not appear in the movie at all.
While the movie characters are technically also from the book, the characters used in the game are exclusively from the movie and don't show any connection to the book counterpart, the book characters used in the game don't appear at all in the movie and are exported from the book, albeit with a different design and/or personality - therefore, these characters count as book chaarcters and the formers don't.