stag's-horn coral vs madrepore

stag's-horn coral and madrepore both are nouns.

Word	Noun	Adjective	Verb	Adverb
stag's-horn coral	Yes	No	No	No
madrepore	Yes	No	No	No

As nouns, madrepore is a hypernym of stag's-horn coral; that is, madrepore is a word with a broader meaning than stag's-horn coral:

stag's-horn coral: large branching coral resembling antlers
madrepore: corals having calcareous skeletons aggregations of which form reefs and islands

Other hypernyms of stag's-horn coral include madriporian coral, stony coral.

stag's-horn coral (noun)	madrepore (noun)
large branching coral resembling antlers	corals having calcareous skeletons aggregations of which form reefs and islands