write-in candidate vs candidate

write-in candidate and candidate both are nouns.

Word	Noun	Adjective	Verb	Adverb
write-in candidate	Yes	No	No	No
candidate	Yes	No	No	No

As nouns, candidate is a hypernym of write-in candidate; that is, candidate is a word with a broader meaning than write-in candidate:

write-in candidate: a candidate for public office whose name does not appear on the ballot and so must be written on the ballot by the voters
candidate: a politician who is running for public office

Other hypernyms of write-in candidate include campaigner, nominee.

write-in candidate (noun)	candidate (noun)
a candidate for public office whose name does not appear on the ballot and so must be written on the ballot by the voters	someone who is considered for something (for an office or prize or honor etc.)
	a politician who is running for public office