notion vs whimsey

notion and whimsey both are nouns.

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

As nouns, notion and whimsey are synonyms defined as:

Other synonyms of notion include whim, whimsy.

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