schoolbook vs primer

schoolbook and primer both are nouns.

Word	Noun	Adjective	Verb	Adverb
schoolbook	Yes	No	No	No
primer	Yes	No	No	No

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

Other hyponyms of schoolbook include crammer, introduction, reader.

schoolbook (noun)	primer (noun)
a book prepared for use in schools or colleges	any igniter that is used to initiate the burning of a propellant
	the first or preliminary coat of paint or size applied to a surface
	an introductory textbook