Democrat vs politician

Democrat and politician both are nouns.

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

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

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

Democrat (noun)	politician (noun)
a member of the Democratic Party	a person active in party politics
	a leader engaged in civil administration
	a schemer who tries to gain advantage in an organization in sly or underhanded ways