Final answer:
The text of an opera is known as a libretto, which contains all the dialogue and lyrics sung by the characters, differentiating it from a screenplay or a storybook.
Step-by-step explanation:
The text of an opera is called a libretto. It is essentially the script of the opera, containing all the dialogue and lyrics that the characters sing. Unlike a screenplay, which is for films, or a storybook, which typically refers to a book of stories for children, the libretto is specific to the operatic art form. It includes both the spoken dialogue, if there is any, and the lyrics for recitatives and arias. A recitative, on the other hand, is a style of delivery in opera where the text is sung in a way that mimics natural speech, rather than the more melodic aria.