politician vs party man

politician and party man both are nouns.

Word	Noun	Adjective	Verb	Adverb
politician	Yes	No	No	No
party man	Yes	No	No	No

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

politician: a person active in party politics
party man: a member of a political party who follows strictly the party line

politician (noun)	party man (noun)
a person active in party politics	a member of a political party who follows strictly the party line
a leader engaged in civil administration
a schemer who tries to gain advantage in an organization in sly or underhanded ways