metaphor vs rhetorical device

metaphor

noun
  • The use of a word or phrase to refer to something other than its literal meaning, invoking an implicit similarity between the thing described and what is denoted by the word or phrase. 

  • A word or phrase used in such implied comparison. 

  • The use of an everyday object or concept to represent an underlying facet of the computer and thus aid users in performing tasks. 

verb
  • To use a metaphor. 

  • To describe by means of a metaphor. 

rhetorical device

noun
  • A phrase (set phrase or created phrase) that uses reduplication, onomatopoeia, or other phonetic markers that increase memorability and “musicality” (making rhetoric pleasing or entertaining). 

How often have the words metaphor and rhetorical device occurred in a corpus of books? (source: Google Ngram Viewer )