antithesis vs rhetorical device

antithesis and rhetorical device both are nouns.

Word	Noun	Adjective	Verb	Adverb
antithesis	Yes	No	No	No
rhetorical device	Yes	No	No	No

As nouns, rhetorical device is a hypernym of antithesis; that is, rhetorical device is a word with a broader meaning than antithesis:

antithesis: the juxtaposition of contrasting words or ideas to give a feeling of balance
rhetorical device: a use of language that creates a literary effect (but often without regard for literal significance)

antithesis (noun)	rhetorical device (noun)
the juxtaposition of contrasting words or ideas to give a feeling of balance	a use of language that creates a literary effect (but often without regard for literal significance)
exact opposite