In the beginning of the book The Lord of the Flies, Piggy gave the idea of choosing a chief. By choosing a chief, the author tried to show how the boys still needed come sort of an adult figure because they are afraid of making the wrong decision. Choosing Ralph as chief also shows the tension of Jack wanting the power which brings them to a point of separation between the group. In the movie, the boys were in a military school which already made Ralph chief for being in a higher rank than the other boys. This change does not show the real meaning of it and how this made the groups separate.
The boys, in the movie, oppose to the book, come from the United States. The book tells us the boys were from England because William Golding wanted to show the drastic change of civilized young boys to savages. The book also takes place in World War II when the boys were evacuating England, but the airplane got shot and crashed on the island. William Golding made an allegory of this situation with World War II to show how it also changed their way of being civilized to becoming savages. It also compares Jack's tribe after separation from Ralph's group to Hitler with the Nazi's because both groups will kill anyone who is against their tribe/group.
As the movie comes to an end, Simon was killed for a different reason. In the movie, Simon was killed by running with a glow stick to warn the boys about there being no beast. In the book, Simon was killed because of his appearance because his face was covered in blood and mud which made the boys think it was he beast when actually it was Simon. This also goes with the boys becoming savages. This change does not go with the book and just takes away the real meaning of the boys becoming complete savages after killing Simon.
Between Harry Hook's version of The Lord of the Flies and the book by William Golding, their differences are very noticeable: such as the boys not choosing a chief in the beginning, the boys not being from England, and how Simon was killed for a different reason.