mutism vs muteness

mutism and muteness both are nouns.

Word	Noun	Adjective	Verb	Adverb
mutism	Yes	No	No	No
muteness	Yes	No	No	No

As nouns, mutism and muteness are synonyms defined as:

mutism and muteness: the condition of being unable or unwilling to speak

mutism (noun)	muteness (noun)
the condition of being unable or unwilling to speak	a refusal to speak when expected
	the condition of being unable or unwilling to speak