boy vs male child

boy and male child both are nouns.

Word	Noun	Adjective	Verb	Adverb
boy	Yes	No	No	No
male child	Yes	No	No	No

As nouns, boy and male child are synonyms defined as:

boy (noun)	male child (noun)
a youthful male person	a youthful male person
(ethnic slur) offensive and disparaging term for Black man
a friendly informal reference to a grown man
a male human offspring