Brown vs John Brown

Brown and John Brown both are nouns.

Word	Noun	Adjective	Verb	Adverb
Brown	Yes	No	No	No
John Brown	Yes	No	No	No

As nouns, Brown and John Brown are synonyms defined as:

Brown and John Brown: abolitionist who was hanged after leading an unsuccessful raid at Harper's Ferry, Virginia (1800-1859)

Brown (noun)	John Brown (noun)
a university in Rhode Island	abolitionist who was hanged after leading an unsuccessful raid at Harper's Ferry, Virginia (1800-1859)
abolitionist who was hanged after leading an unsuccessful raid at Harper's Ferry, Virginia (1800-1859)
Scottish botanist who first observed the movement of small particles in fluids now known a Brownian motion (1773-1858)