"Unlike television where the writer is in charge, in the movie world, the Director is king. The director of a movie is the commander and chief of a set. What he or she says goes everything from the look of the overall picture to the action contained within. They literally direct the movements of the actors, the choices of the shots, the rewrites of the script and the final edits. The director works closely with all major departments to make sure the project has all the elements they need. From the Cinematographer to the Gaffer to the Editor, they all take their direction from the Director"
http://filmtvcareers.about.com/od/basics/p/CP_FilmDirector.htm