sea pen vs actinozoan

sea pen and actinozoan both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea pen	Yes	No	No	No
actinozoan	Yes	No	No	No

As nouns, actinozoan is a hypernym of sea pen; that is, actinozoan is a word with a broader meaning than sea pen:

sea pen: fleshy featherlike warm-water colonies
actinozoan: sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed

Other hypernyms of sea pen include anthozoan.

sea pen (noun)	actinozoan (noun)
fleshy featherlike warm-water colonies	sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed