cnidarian vs actinozoan

cnidarian and actinozoan both are nouns.

Word	Noun	Adjective	Verb	Adverb
cnidarian	Yes	No	No	No
actinozoan	Yes	No	No	No

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

cnidarian: radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms
actinozoan: sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed

Other hyponyms of cnidarian include polyp, medusa, medusan, medusoid, jellyfish, scyphozoan, hydroid, hydrozoan, anthozoan.

cnidarian (noun)	actinozoan (noun)
radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms	sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed