reviewer vs commentator

reviewer and commentator both are nouns.

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

As nouns, reviewer and commentator are synonyms defined as:

reviewer and commentator: a writer who reports and analyzes events of the day

reviewer (noun)	commentator (noun)
a writer who reports and analyzes events of the day	a writer who reports and analyzes events of the day
someone who reads manuscripts and judges their suitability for publication	an expert who observes and comments on something