ecphonesis vs rhetorical device

ecphonesis and rhetorical device both are nouns.

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

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

ecphonesis: an exclamatory rhetorical device
rhetorical device: a use of language that creates a literary effect (but often without regard for literal significance)

ecphonesis (noun)	rhetorical device (noun)
an exclamatory rhetorical device	a use of language that creates a literary effect (but often without regard for literal significance)