oligochaete vs annelid worm

oligochaete and annelid worm both are nouns.

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

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

oligochaete: hermaphroditic terrestrial and aquatic annelids having bristles borne singly along the length of the body
annelid worm: worms with cylindrical bodies segmented both internally and externally

Other hypernyms of oligochaete include annelid, segmented worm.

oligochaete (noun)	annelid worm (noun)
hermaphroditic terrestrial and aquatic annelids having bristles borne singly along the length of the body	worms with cylindrical bodies segmented both internally and externally