tunicate vs salpa

tunicate and salpa both are nouns.

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

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

tunicate: 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 tunicate include ascidian, salp, doliolum, larvacean, appendicularia.

tunicate (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