hydrozoan vs coelenterate

hydrozoan and coelenterate both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydrozoan	Yes	No	No	No
coelenterate	Yes	No	No	No

As nouns, coelenterate is a hypernym of hydrozoan; that is, coelenterate is a word with a broader meaning than hydrozoan:

hydrozoan: colonial coelenterates having the polyp phase dominant
coelenterate: radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms

Other hypernyms of hydrozoan include cnidarian.

hydrozoan (noun)	coelenterate (noun)
colonial coelenterates having the polyp phase dominant	radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms