political hack vs politician

political hack and politician both are nouns.

Word	Noun	Adjective	Verb	Adverb
political hack	Yes	No	No	No
politician	Yes	No	No	No

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

political hack: a politician who belongs to a small clique that controls a political party for private rather than public ends
politician: a person active in party politics

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

political hack (noun)	politician (noun)
a politician who belongs to a small clique that controls a political party for private rather than public ends	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