rationalism vs ism

rationalism and ism both are nouns.

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

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

rationalism: the doctrine that reason is the right basis for regulating conduct
ism: a belief (or system of beliefs) accepted as authoritative by some group or school

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

rationalism (noun)	ism (noun)
the doctrine that reason is the right basis for regulating conduct	a belief (or system of beliefs) accepted as authoritative by some group or school
(philosophy) the doctrine that knowledge is acquired by reason without resort to experience
the theological doctrine that human reason rather than divine revelation establishes religious truth