schoolchild vs boarder

schoolchild and boarder both are nouns.

Word	Noun	Adjective	Verb	Adverb
schoolchild	Yes	No	No	No
boarder	Yes	No	No	No

As nouns, boarder is a hyponym of schoolchild; that is, boarder is a word with a more specific, narrower meaning than schoolchild:

schoolchild: a young person attending school (up through senior high school)
boarder: a pupil who lives at school during term time

Other hyponyms of schoolchild include day boarder, latchkey child, schoolboy.

schoolchild (noun)	boarder (noun)
a young person attending school (up through senior high school)	a tenant in someone's house
	a pupil who lives at school during term time
	someone who forces their way aboard ship