printer vs proofreader

printer and proofreader both are nouns.

Word	Noun	Adjective	Verb	Adverb
printer	Yes	No	No	No
proofreader	Yes	No	No	No

As nouns, proofreader is a hyponym of printer; that is, proofreader is a word with a more specific, narrower meaning than printer:

printer: someone whose occupation is printing
proofreader: someone who reads proof in order to find errors and mark corrections

Other hyponyms of printer include compositor, setter, typesetter, typographer, reader.

printer (noun)	proofreader (noun)
a machine that prints	someone who reads proof in order to find errors and mark corrections
(computer science) an output device that prints the results of data processing
someone whose occupation is printing