centerboard vs sliding keel

centerboard and sliding keel both are nouns.

Word	Noun	Adjective	Verb	Adverb
centerboard	Yes	No	No	No
sliding keel	Yes	No	No	No

As nouns, centerboard and sliding keel are synonyms defined as:

centerboard and sliding keel: a retractable fin keel used on sailboats to prevent drifting to leeward

Other synonyms of centerboard include centreboard, drop keel.

centerboard (noun)	sliding keel (noun)
a retractable fin keel used on sailboats to prevent drifting to leeward	a retractable fin keel used on sailboats to prevent drifting to leeward