As the name suggests, the person who writes the story of the film is the story writer. The characters are visualized as those in a story, and a flow of events and incidents are penned down. The story writer is the man who writes the story like the ones in a book or novel. With the help of the story, the screenplay is written.
The visual impact, sound effects are added to the plot to make a screenplay- a screenplay is a ‘textual movie’ whereas a story is the flow of events which may or may not be made into a movie. Whatever the author writes, the end product is called a story. The story is in its raw form- to make its movie a script is written, which is very close to the story but the dialogues are added to it. More than narrative, the script will contain more conversations. The screenplay is drawn from the script.