candidate vs politician

candidate and politician both are nouns.

Word	Noun	Adjective	Verb	Adverb
candidate	Yes	No	No	No
politician	Yes	No	No	No

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

Other hypernyms of candidate include pol, political leader, politico.

candidate (noun)	politician (noun)
someone who is considered for something (for an office or prize or honor etc.)	a person active in party politics
a politician who is running for public office	a leader engaged in civil administration
	a schemer who tries to gain advantage in an organization in sly or underhanded ways