aplomb vs assuredness

aplomb and assuredness both are nouns.

Word	Noun	Adjective	Verb	Adverb
aplomb	Yes	No	No	No
assuredness	Yes	No	No	No

As nouns, aplomb and assuredness are synonyms defined as:

Other synonyms of aplomb include cool, poise, sang-froid.

aplomb (noun)	assuredness (noun)
great coolness and composure under strain	great coolness and composure under strain