There are a lot of different ways a script or idea for a movie or TV show can be sold. Here's what these terms mean and how to use them correctly:
"I sold a pilot" usually means that you sold the pilot for a TV show that you wrote on “spec” or speculatively — meaning that you wrote the script hoping to sell it, but without a guarantee that you would. If you sold a pilot, it means you wrote a pilot and someone bought it in anticipation of producing a television show.
By contrast, "I sold a show" likely means you sold a pitch or idea for a show to be recorded as the pilot episode of a TV series. The script probably hasn't been developed at this point, but the network, streamer, studio or production company bought the idea and said, "Let's make this show."
A show can be sold with or without a script, depending on the writer's track record. Writers who have already sold a script are able to sell just the pitch; new writers need to write the script.
The script refers to the script for the pilot episode, not the script for the entire season or series.
Similarly, "I sold a screenplay" means that you sold a script for a movie that you wrote on spec, whereas "I sold a movie" could mean you sold a pitch for a movie without having the script yet, which some established writers are able to do.
You wouldn’t use this interchangeably with “I sold a show.” "Screenplay" applies to features, i.e., movies or films. "Teleplay" is the television equivalent of "screenplay," but it's a fairly old term that's not commonly used anymore.
Writing the spec pilot script first does allow for more creative control, even for established writers.
If you sell the pitch, the company that buys it would pay to develop the script and will have a lot of input into the process. This is not a bad thing. Development executives are generally very bright people with good taste and a wealth of experience making successful films and shows. They also are well-acquainted with the needs of the network or studio that they work for, as well as the preferences of those who will make the ultimate decision: greenlighting your script to production or killing it forever.
When you’re just breaking in, you’ll need something for people to read, so you’ll need to actually write the screenplay first.
"I sold a script" could apply to TV or movies. If you say you sold a script, that means that you wrote an original script, and a network, studio, streamer or production company bought it to record and turn into a movie or the pilot episode of a TV show.
If you don’t know whether the person writes screenplays or for TV, it would be reasonable to ask if the script was for a TV show or a movie. “Sold a script” is ambiguous and doesn’t indicate whether it’s a movie or a pilot.
"Sold a spec" can refer to one of two distinct situations, neither of which you are likely to encounter.
The first situation is one in which a writer wrote an episode of an existing series on spec, hoping to sell it to the producers of the series. This was a common practice in television thirty years ago, but it rarely happens now. Specs of existing series are still written, but mostly as a sample to showcase the writer’s ability to write for an existing series and in another writer’s voice.
The other situation in which “sold a spec” might apply is one in which a writer sold a pilot that was written on spec, but the writer would much more likely say, “I sold a pilot.”