hydroid vs hydrozoan

hydroid and hydrozoan both are nouns.

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

As nouns, hydroid and hydrozoan are synonyms defined as:

hydroid and hydrozoan: colonial coelenterates having the polyp phase dominant

hydroid (noun)	hydrozoan (noun)
colonial coelenterates having the polyp phase dominant	colonial coelenterates having the polyp phase dominant