Argonaut vs octopod

Argonaut and octopod both are nouns.

Word	Noun	Adjective	Verb	Adverb
Argonaut	Yes	No	No	No
octopod	Yes	No	No	No

As nouns, octopod is a hypernym of Argonaut; that is, octopod is a word with a broader meaning than Argonaut:

Argonaut: cephalopod mollusk of warm seas whose females have delicate papery spiral shells
octopod: a cephalopod with eight arms but lacking an internal shell

Argonaut (noun)	octopod (noun)
cephalopod mollusk of warm seas whose females have delicate papery spiral shells	a cephalopod with eight arms but lacking an internal shell
(Greek mythology) one of the heroes who sailed with Jason in search of the Golden Fleece