larvacean vs urochord

larvacean and urochord both are nouns.

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

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

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

Other hypernyms of larvacean include tunicate, urochordate.

larvacean (noun)	urochord (noun)
any member of the class Larvacea	a notochord of a larval tunicate typically confined to the caudal region
	primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva