passion vs fieriness

passion and fieriness both are nouns.

Word	Noun	Adjective	Verb	Adverb
passion	Yes	No	No	No
fieriness	Yes	No	No	No

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

passion (noun)	fieriness (noun)
the trait of being intensely emotional	the heat or the color of fire
any object of warm affection or devotion	a passionate and quick-tempered nature
a strong feeling or emotion
a feeling of strong sexual desire
an irrational but irresistible motive for a belief or action
something that is desired intensely