whimsy vs notion

whimsy and notion both are nouns.

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

As nouns, whimsy and notion are synonyms defined as:

Other synonyms of whimsy include whim, whimsey.

whimsy (noun)	notion (noun)
the trait of acting unpredictably and more from whim or caprice than from reason or judgment	(usually plural) small personal articles or clothing or sewing items
an odd or fanciful or capricious idea	a general inclusive concept
	an odd or fanciful or capricious idea
	a vague idea in which some confidence is placed