schoolfellow vs classmate

schoolfellow and classmate both are nouns.

Word	Noun	Adjective	Verb	Adverb
schoolfellow	Yes	No	No	No
classmate	Yes	No	No	No

As nouns, schoolfellow and classmate are synonyms defined as:

Other synonyms of schoolfellow include class fellow, schoolmate.

schoolfellow (noun)	classmate (noun)
an acquaintance that you go to school with	an acquaintance that you go to school with