What differentiates stories that are suited for film from stories that are suited for television depends primarily on the content and how the story unfolds. For a book or story to be considered for film, the conflict must be resolvable within the typical length of movie, which is about two hours. However, for television, the story can continue to unfold as long as the network is willing to continue the series. Per writer and producer, Annelise Dekker, a book that can lend itself to many story arcs and has a rich setting will usually translate better to television.
The writing styles and formats for books and screenplays are very different. As screenwriter, Brian Dillon, explains, writing for the screen is about structure, action and visuals, while writing for the page is about the language and details. A screenplay is a base document that many people will influence along the way and rely on to execute the project, so it's important for a screenwriter to avoid the story specific details and heavy dialogue. Writing for page gives a writer complete freedom to address every aspect of the human condition, which can be very freeing.