altar boy vs boy

altar boy and boy both are nouns.

Word	Noun	Adjective	Verb	Adverb
altar boy	Yes	No	No	No
boy	Yes	No	No	No

As nouns, boy is a hypernym of altar boy; that is, boy is a word with a broader meaning than altar boy:

Other hypernyms of altar boy include acolyte, male child.

altar boy (noun)	boy (noun)
a boy serving as an acolyte	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