The one difference you could discuss is the internal monologue of Simon as the novel progresses. He has internal thoughts that could be better expressed through interesting cinematography (like how the recent Dune movie handles Paul's visions/dreams.) He says the beast doesn't exist and that "maybe it's only us." The visions he has and his "conversation" with the Lord of the Flies could be made much more unsettling - like a horror film with the ultimate villain being expressed through the the death of Simon (loss of philosophical understanding and responsibility)and Piggy (loss of rational thinking)
