sea anemone vs actinian

sea anemone and actinian both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea anemone	Yes	No	No	No
actinian	Yes	No	No	No

As nouns, actinian is a hyponym of sea anemone; that is, actinian is a word with a more specific, narrower meaning than sea anemone:

sea anemone: marine polyps that resemble flowers but have oral rings of tentacles; differ from corals in forming no hard skeleton
actinian: any sea anemone or related animal

Other hyponyms of sea anemone include actinia, actiniarian.

sea anemone (noun)	actinian (noun)
marine polyps that resemble flowers but have oral rings of tentacles; differ from corals in forming no hard skeleton	any sea anemone or related animal