common man vs common person

common man and common person both are nouns.

Word	Noun	Adjective	Verb	Adverb
common man	Yes	No	No	No
common person	Yes	No	No	No

As nouns, common man and common person are synonyms defined as:

Other synonyms of common man include commoner.

common man (noun)	common person (noun)
a person who holds no title	a person who holds no title