fugaciousness vs transience

fugaciousness and transience both are nouns.

Word	Noun	Adjective	Verb	Adverb
fugaciousness	Yes	No	No	No
transience	Yes	No	No	No

As nouns, transience is a hypernym of fugaciousness; that is, transience is a word with a broader meaning than fugaciousness:

fugaciousness: the lack of enduring qualities (used chiefly of plant parts)
transience: an impermanence that suggests the inevitability of ending or dying

Other hypernyms of fugaciousness include transiency, transitoriness.

fugaciousness (noun)	transience (noun)
the lack of enduring qualities (used chiefly of plant parts)	an impermanence that suggests the inevitability of ending or dying
	the attribute of being brief or fleeting