classmate vs schoolfellow

classmate and schoolfellow both are nouns.

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

As nouns, classmate and schoolfellow are synonyms defined as:

Other synonyms of classmate include class fellow, schoolmate.

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