So now that I'm scribbling away at my novel, I realize just how different it is from screenwriting. I knew intellectually how different the two endeavors were, but am now getting it at a visceral level.
There are, of course, similarities. The three-act structure works well, generally, in both. But it's not required in a novel. Good dialogue is a must in both, etc.
But thereafter - geez. Things diverge. Screenplays are essentially a blueprint. After it's written, other folks come along and interpret it - the director, actors, producers, editors, etc. Movies and TV are the product of many different people. Because of this, the screenwriter must trust that people read a bit between the lines. You write prose to describe the actions taking place on screen, and then dialogue. That's it! There's very little description. You can nudge the dialogue into an emotional direction with an occasional parenthetical, but after that, it's all up to how the director and editor deal with the actor's performance. The only way to really get into a character's head is with a telling close up or voiceover, which I often find annoying.
In a novel, if you just leave the bare dialogue hanging out there with the equivelent of an occasional parenthetical, readers get confused. There's no actor interpreting things for them. They can't see facial expressions. They get no reaction shots. So you have to give the reader more. A lot more. I'm writing in the first person, and at first I resisted giving too many of my character's thought to the reader. Having been trained in screenwriting, I figure folks will read into the dialogue and get the subtext.
But it doesn't work that way in a novel. As I've added more inner thoughts from my protagonist and shown his inner turmoil, the meaning behind the dialogue becomes clearer for my readers. They like the hero more. They hate the antogonist more. They are far more invested.
There are more ways the types of writing differ, but I need to go off and do some more of that writing. So perhaps more later.
Writing is a constant learning experience. That's one more reason why I like it!