ephemeralness vs fleetingness

ephemeralness and fleetingness both are nouns.

Word	Noun	Adjective	Verb	Adverb
ephemeralness	Yes	No	No	No
fleetingness	Yes	No	No	No

As nouns, ephemeralness and fleetingness are synonyms defined as:

ephemeralness and fleetingness: the property of lasting for a very short time

Other synonyms of ephemeralness include ephemerality.

ephemeralness (noun)	fleetingness (noun)
the property of lasting for a very short time	the property of lasting for a very short time