politician vs demagog

politician and demagog both are nouns.

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

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

politician: a person active in party politics
demagog: a political leader who seeks support by appealing to popular passions and prejudices

politician (noun)	demagog (noun)
a person active in party politics	a political leader who seeks support by appealing to popular passions and prejudices
a leader engaged in civil administration
a schemer who tries to gain advantage in an organization in sly or underhanded ways