asyndeton vs rhetorical device

asyndeton and rhetorical device both are nouns.

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

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

asyndeton: the omission of conjunctions where they would normally be used
rhetorical device: a use of language that creates a literary effect (but often without regard for literal significance)

asyndeton (noun)	rhetorical device (noun)
the omission of conjunctions where they would normally be used	a use of language that creates a literary effect (but often without regard for literal significance)