archiannelid vs annelid worm

archiannelid and annelid worm both are nouns.

Word	Noun	Adjective	Verb	Adverb
archiannelid	Yes	No	No	No
annelid worm	Yes	No	No	No

As nouns, annelid worm is a hypernym of archiannelid; that is, annelid worm is a word with a broader meaning than archiannelid:

archiannelid: small primitive marine worm lacking external segmentation and resembling polychaete larvae
annelid worm: worms with cylindrical bodies segmented both internally and externally

Other hypernyms of archiannelid include annelid, segmented worm.

archiannelid (noun)	annelid worm (noun)
small primitive marine worm lacking external segmentation and resembling polychaete larvae	worms with cylindrical bodies segmented both internally and externally