review vs reviewer

review and reviewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
review	Yes	No	Yes	No
reviewer	Yes	No	No	No

review (noun)	reviewer (noun)
a subsequent examination of a patient for the purpose of monitoring earlier treatment	a writer who reports and analyzes events of the day
practice intended to polish performance or refresh the memory	someone who reads manuscripts and judges their suitability for publication
a formal or official examination
(law) a judicial reexamination of the proceedings of a court (especially by an appellate court)
a new appraisal or evaluation
a summary at the end that repeats the substance of a longer discussion
an essay or article that gives a critical evaluation (as of a book or play)
a variety show with topical sketches and songs and dancing and comedians
a periodical that publishes critical essays on current affairs or literature or art
(accounting) a service (less exhaustive than an audit) that provides some assurance to interested parties as to the reliability of financial data

review (verb)	reviewer (verb)
look at again; examine again
look back upon (a period of time, sequence of events); remember
hold a review (of troops)
refresh one's memory
appraise critically