salp vs urochord

salp and urochord both are nouns.

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

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

salp: minute floating marine tunicate having a transparent body with an opening at each end
urochord: primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva

Other hypernyms of salp include tunicate, urochordate.

salp (noun)	urochord (noun)
minute floating marine tunicate having a transparent body with an opening at each end	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