drop keel vs fin keel

drop keel and fin keel both are nouns.

Word	Noun	Adjective	Verb	Adverb
drop keel	Yes	No	No	No
fin keel	Yes	No	No	No

As nouns, fin keel is a hypernym of drop keel; that is, fin keel is a word with a broader meaning than drop keel:

drop keel: a retractable fin keel used on sailboats to prevent drifting to leeward
fin keel: a metal plate projecting from the keel of a shallow vessel to give it greater lateral stability

drop keel (noun)	fin keel (noun)
a retractable fin keel used on sailboats to prevent drifting to leeward	a metal plate projecting from the keel of a shallow vessel to give it greater lateral stability