politician vs candidate

politician and candidate both are nouns.

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

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

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