closer vs relief pitcher

closer and relief pitcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
closer	Yes	No	No	Yes
relief pitcher	Yes	No	No	No

As nouns, relief pitcher is a hypernym of closer; that is, relief pitcher is a word with a broader meaning than closer:

closer: (baseball) a relief pitcher who can protect a lead in the last inning or two of the game
relief pitcher: a pitcher who does not start the game

Other hypernyms of closer include fireman, reliever.

closer (noun)	relief pitcher (noun)
(baseball) a relief pitcher who can protect a lead in the last inning or two of the game	a pitcher who does not start the game
a person who closes something

closer (adverb)	relief pitcher (adverb)
(comparative of `near' or `close') within a shorter distance