fun vs whimsicality

fun and whimsicality both are nouns.

Word	Noun	Adjective	Verb	Adverb
fun	Yes	No	No	No
whimsicality	Yes	No	No	No

As nouns, whimsicality is a hyponym of fun; that is, whimsicality is a word with a more specific, narrower meaning than fun:

fun (noun)	whimsicality (noun)
activities that are enjoyable or amusing	the trait of behaving like an imp
violent and excited activity	the trait of acting unpredictably and more from whim or caprice than from reason or judgment
a disposition to find (or make) causes for amusement
verbal wit or mockery (often at another's expense but not to be taken seriously)