Although different, the book and movie of The Witches are both very good. Here are some differences between the book and the movie.
In the book and movie, the grandma tells the boy (Luke, in the movie) all about witches. Both versions include a girl who, after a witch attacks her, is trapped inside a painting. That part is very interesting and very neat. Some other similarities are that the boy/Luke is turned into a mouse both times, but in the movie, Luke turns back into a boy at the end, and in the book, the boy stays a mouse.
In case you're wondering how the boy/Luke was turned into a mouse in the first place, the witches had a special formula (Formula 86 Delayed-Action Mouse Maker) to turn things into mice. They got ahold of him and made him drink it, only in the book, it was at the witches' annual meeting, and in the movie, it was in Luke's hotel room.
In the book and movie, the boy goes into the Grand High Witch's room to locate the formula so that he can pour it into the witches' food and turn them all into mice! In the movie, however, this feat was probably more dangerous than in the book, because in the movie, there was a CAT in her room! He escaped, however, with the formula, but in the movie, it was hidden in a book in her dresser, and in the book, it was under the mattress.
Finally, in the movie, the Grand High Witch has a slave who helps her with her mask, clothes and work.
One of the things I especially enjoyed about the movie The Witches was that it was so realistically scary. You felt as if you were really the boy, and all the scary happenings were really taking place. I love the story of the witches!