atonality vs atonalism

atonality and atonalism both are nouns.

Word	Noun	Adjective	Verb	Adverb
atonality	Yes	No	No	No
atonalism	Yes	No	No	No

As nouns, atonality and atonalism are synonyms defined as:

atonality and atonalism: the absence of a key; alternative to the diatonic system

atonality (noun)	atonalism (noun)
the absence of a key; alternative to the diatonic system	the absence of a key; alternative to the diatonic system