synchronism vs synchrony

synchronism and synchrony both are nouns.

Word	Noun	Adjective	Verb	Adverb
synchronism	Yes	No	No	No
synchrony	Yes	No	No	No

As nouns, synchronism and synchrony are synonyms defined as:

synchronism and synchrony: the relation that exists when things occur at the same time

Other synonyms of synchronism include synchroneity, synchronicity, synchronisation, synchronization, synchronizing.

synchronism (noun)	synchrony (noun)
the relation that exists when things occur at the same time	the relation that exists when things occur at the same time