oligochaete vs segmented worm

oligochaete and segmented worm both are nouns.

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

As nouns, segmented worm is a hypernym of oligochaete; that is, segmented 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
segmented worm: worms with cylindrical bodies segmented both internally and externally

Other hypernyms of oligochaete include annelid, annelid worm.

oligochaete (noun)	segmented 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