old salt vs sailor

old salt and sailor both are nouns.

Word	Noun	Adjective	Verb	Adverb
old salt	Yes	No	No	No
sailor	Yes	No	No	No

As nouns, sailor is a hypernym of old salt; that is, sailor is a word with a broader meaning than old salt:

Other hypernyms of old salt include crewman.

old salt (noun)	sailor (noun)
a man who serves as a sailor	a stiff hat made of straw with a flat crown
	any member of a ship's crew
	a serviceman in the navy