There is usually a lot of confusion when it comes to these two terms. Some sources say that there is no (practical) difference between the two while other sources talk of various kinds of differences. However, I have not run into any authentic source that answers my question.
My question is as follows:
In the context to a film/TV show etc., what is the difference between a script and a screenplay? (There ought to be a difference because the credits always have different sections for script and screenplay).
Further, in context to the theatre, is there any difference between the two words (I have not come across anyone using the term "screenplay" in context of the theatre)? Are the two interchangeable? If not, what is the difference in the writing style for both.