notion vs belief

notion and belief both are nouns.

Word	Noun	Adjective	Verb	Adverb
notion	Yes	No	No	No
belief	Yes	No	No	No

As nouns, notion and belief are synonyms defined as:

Other synonyms of notion include feeling, impression, opinion.

notion (noun)	belief (noun)
(usually plural) small personal articles or clothing or sewing items	any cognitive content held as true
a general inclusive concept	a vague idea in which some confidence is placed
an odd or fanciful or capricious idea
a vague idea in which some confidence is placed