furiousness vs fierceness

furiousness and fierceness both are nouns.

Word	Noun	Adjective	Verb	Adverb
furiousness	Yes	No	No	No
fierceness	Yes	No	No	No

As nouns, furiousness and fierceness are synonyms defined as:

Other synonyms of furiousness include ferocity, fury, vehemence, violence, wildness.

furiousness (noun)	fierceness (noun)
the property of being wild or turbulent	the property of being wild or turbulent