larvacean vs urochordate

larvacean and urochordate both are nouns.

Word	Noun	Adjective	Verb	Adverb
larvacean	Yes	No	No	No
urochordate	Yes	No	No	No

As nouns, urochordate is a hypernym of larvacean; that is, urochordate is a word with a broader meaning than larvacean:

larvacean: any member of the class Larvacea
urochordate: primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva

Other hypernyms of larvacean include tunicate, urochord.

larvacean (noun)	urochordate (noun)
any member of the class Larvacea	primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva