reviewer vs writer

reviewer and writer both are nouns.

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

As nouns, writer is a hypernym of reviewer; that is, writer is a word with a broader meaning than reviewer:

reviewer: a writer who reports and analyzes events of the day
writer: writes (books or stories or articles or the like) professionally (for pay)

Other hypernyms of reviewer include author.

reviewer (noun)	writer (noun)
a writer who reports and analyzes events of the day	writes (books or stories or articles or the like) professionally (for pay)
someone who reads manuscripts and judges their suitability for publication	a person who is able to write and has written something