A screenwriter is a screenwriter is a screenwriter. It's what they write that's different. Many screenwriters can write for TV, film, comedies and dramas, but the way they approach the work changes considerably with the specific type of project.
TV comedy writers, for example, not only have to be funny, but they also have to be able to work in a highly collaborative, sometimes pressure-filled environment. Sitcom screenwriting is a group effort. A typical sitcom might have 10 or 12 full-time staff writers. Most of their day is spent in the writers' room, a large conference room where the writers meet to brainstorm story ideas, beat out the plot points for each episode, pitch jokes and continuously revise scripts until they're ready to be shot.
Once an episode has been outlined in detail by the whole group, one writer or writing team is assigned to write the first draft of the script. When the script is finally shot weeks or months later, it will have undergone so many revisions that it might not even resemble the original version. For this reason, TV comedy writers need thick skins to avoid getting hurt or angry when their best jokes are cut by a studio executive or shot down by a senior writer. In other words, there's not a lot of personal ownership in TV comedy screenwriting. It's all about being part of the team.
TV drama screenwriting is also highly team-oriented, but writers have a little more ownership of their individual scripts. On some TV dramas, the show runner or executive producer actually writes all of the episodes and then has the staff writers help revise and punch them up. On other shows, it's the opposite, with staff writers writing individual episodes and the show runner revising them all himself. Either way, when a TV drama screenwriter is credited with an episode, you can be sure that at least some of the lines were actually written by that person, which isn't the case with TV comedy screenwriters.
Feature film screenwriters are much more solitary creatures. Film screenwriters work closely with directors and producers to develop an idea, but once the story and characters are defined, the screenwriter is allowed to go off and write more or less in peace. Of course, he may be asked to submit several revisions before the script is accepted. A screenwriter may work for years on a single script, but the compensation is considerable.
For films produced by major Hollywood studios, it's not uncommon for several screenwriters to be credited with the same script. Unless two of those writers are a writing team, it's unlikely that any of them actually worked together on the script. More often than not, a single screenwriter was originally hired to write the script, then other screenwriters were brought in to punch it up. Maybe some romantic dialogue needed re-working or some of the jokes were falling flat. Sometimes punch-up writers aren't credited at all.
Now let's tackle the toughest topic of all: how to break into the screenwriting business.