peer review vs referee

peer review is not a noun while referee is a noun.

Word	Noun	Adjective	Verb	Adverb
peer review	No	No	Yes	No
referee	Yes	No	Yes	No

As verbs, peer review and referee are synonyms defined as:

peer review (noun)	referee (noun)
	(sports) the chief official (as in boxing or American football) who is expected to ensure fair play
	someone who reads manuscripts and judges their suitability for publication
	an attorney appointed by a court to investigate and report on a case

peer review (verb)	referee (verb)
evaluate professionally a colleague's work	evaluate professionally a colleague's work
	be a referee or umpire in a sports competition