Joe Blow vs man in the street

Joe Blow and man in the street both are nouns.

Word	Noun	Adjective	Verb	Adverb
Joe Blow	Yes	No	No	No
man in the street	Yes	No	No	No

As nouns, Joe Blow and man in the street are synonyms defined as:

Other synonyms of Joe Blow include Joe Bloggs, John Doe.

Joe Blow (noun)	man in the street (noun)
a hypothetical average man	a hypothetical average man