male body vs man's body

male body and man's body both are nouns.

Word	Noun	Adjective	Verb	Adverb
male body	Yes	No	No	No
man's body	Yes	No	No	No

As nouns, man's body is a hyponym of male body; that is, man's body is a word with a more specific, narrower meaning than male body:

Other hyponyms of male body include adult male body.

male body (noun)	man's body (noun)
the body of a male human being	the body of an adult man