foster-brother vs male person

foster-brother and male person both are nouns.

Word	Noun	Adjective	Verb	Adverb
foster-brother	Yes	No	No	No
male person	Yes	No	No	No

As nouns, male person is a hypernym of foster-brother; that is, male person is a word with a broader meaning than foster-brother:

foster-brother: your foster brother is a male who is not a son of your parents but who is raised by your parents
male person: a person who belongs to the sex that cannot have babies

Other hypernyms of foster-brother include male.

foster-brother (noun)	male person (noun)
your foster brother is a male who is not a son of your parents but who is raised by your parents	a person who belongs to the sex that cannot have babies