impermanence vs impermanency

impermanence and impermanency both are nouns.

Word	Noun	Adjective	Verb	Adverb
impermanence	Yes	No	No	No
impermanency	Yes	No	No	No

As nouns, impermanence and impermanency are synonyms defined as:

impermanence and impermanency: the property of not existing for indefinitely long durations

impermanence (noun)	impermanency (noun)
the property of not existing for indefinitely long durations	the property of not existing for indefinitely long durations