sail vs luff

sail and luff both are nouns.

Word	Noun	Adjective	Verb	Adverb
sail	Yes	No	Yes	No
luff	Yes	No	Yes	No

As verbs, luff is a hyponym of sail; that is, luff is a word with a more specific, narrower meaning than sail:

Other hyponyms of sail include run, point, weather, beat, rack, scud, outpoint, tack, wear round, wear ship, change course, gybe, jib, jibe.

sail (noun)	luff (noun)
an ocean trip taken for pleasure	the act of sailing close to the wind
a large piece of fabric (usually canvas fabric) by means of which wind is used to propel a sailing vessel	(nautical) the forward edge of a fore-and-aft sail that is next to the mast
any structure that resembles a sail

sail (verb)	luff (verb)
travel on water propelled by wind	flap when the wind is blowing equally on both sides
move with sweeping, effortless, gliding motions	sail close to the wind
travel on water propelled by wind or by other means
traverse or travel on (a body of water)