populism vs ism

populism and ism both are nouns.

Word	Noun	Adjective	Verb	Adverb
populism	Yes	No	No	No
ism	Yes	No	No	No

As nouns, ism is a hypernym of populism; that is, ism is a word with a broader meaning than populism:

populism: the political doctrine that supports the rights and powers of the common people in their struggle with the privileged elite
ism: a belief (or system of beliefs) accepted as authoritative by some group or school

Other hypernyms of populism include doctrine, philosophical system, philosophy, school of thought.

populism (noun)	ism (noun)
the political doctrine that supports the rights and powers of the common people in their struggle with the privileged elite	a belief (or system of beliefs) accepted as authoritative by some group or school