schoolwork vs prep

schoolwork and prep both are nouns.

Word	Noun	Adjective	Verb	Adverb
schoolwork	Yes	No	No	No
prep	Yes	No	No	No

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

Other hyponyms of schoolwork include classroom project, classwork, preparation, lesson.

schoolwork (noun)	prep (noun)
work, such as schoolwork or piecework, that is done at home	preparatory school work done outside school (especially at home)