unemotionality vs impassivity

unemotionality and impassivity both are nouns.

Word	Noun	Adjective	Verb	Adverb
unemotionality	Yes	No	No	No
impassivity	Yes	No	No	No

As nouns, unemotionality and impassivity are synonyms defined as:

unemotionality and impassivity: apathy demonstrated by an absence of emotional reactions

Other synonyms of unemotionality include emotionlessness, impassiveness, indifference, phlegm, stolidity.

unemotionality (noun)	impassivity (noun)
absence of emotion	apathy demonstrated by an absence of emotional reactions
apathy demonstrated by an absence of emotional reactions