male person vs fellow

male person and fellow both are nouns.

Word	Noun	Adjective	Verb	Adverb
male person	Yes	No	No	No
fellow	Yes	No	No	No

As nouns, fellow is a hyponym of male person; that is, fellow is a word with a more specific, narrower meaning than male person:

male person (noun)	fellow (noun)
a person who belongs to the sex that cannot have babies	a boy or man
	a man who is the lover of a man or woman
	a friend who is frequently in the company of another
	a person who is member of one's class or profession
	an informal form of address for a man
	a member of a learned society
	one of a pair