urochordate vs salpa

urochordate and salpa both are nouns.

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

As nouns, salpa is a hyponym of urochordate; that is, salpa is a word with a more specific, narrower meaning than urochordate:

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

Other hyponyms of urochordate include ascidian, salp, doliolum, larvacean, appendicularia.

urochordate (noun)	salpa (noun)
primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva	minute floating marine tunicate having a transparent body with an opening at each end