extremism vs political theory

extremism and political theory both are nouns.

Word	Noun	Adjective	Verb	Adverb
extremism	Yes	No	No	No
political theory	Yes	No	No	No

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

extremism: any political theory favoring immoderate uncompromising policies
political theory: an orientation that characterizes the thinking of a group or nation

Other hypernyms of extremism include ideology, political orientation.

extremism (noun)	political theory (noun)
any political theory favoring immoderate uncompromising policies	an orientation that characterizes the thinking of a group or nation