By "language of a book" you mean, I think, the terminology of literature, the language we use to talk about writing.
Diction concerns the choice of words to be used. Here is the closest I have come for a definition of
literary device:
Quote:
a particular word pattern, figure of speech, combination of word sounds, etc., used in a literary work to evoke a desired effect or arouse a desired reaction in the reader: rhetorical devices. http://www.infoplease.com/ipd/A0406001.html |
I hope that helps.