composure vs calmness

composure and calmness both are nouns.

Word	Noun	Adjective	Verb	Adverb
composure	Yes	No	No	No
calmness	Yes	No	No	No

As nouns, composure and calmness are synonyms defined as:

Other synonyms of composure include calm, equanimity.

composure (noun)	calmness (noun)
steadiness of mind under stress	steadiness of mind under stress
	a feeling of calm; an absence of agitation or excitement
	an absence of strong winds or rain