irrelevancy vs irrelevance

irrelevancy and irrelevance both are nouns.

Word	Noun	Adjective	Verb	Adverb
irrelevancy	Yes	No	No	No
irrelevance	Yes	No	No	No

As nouns, irrelevancy and irrelevance are synonyms defined as:

irrelevancy and irrelevance: the lack of a relation of something to the matter at hand

irrelevancy (noun)	irrelevance (noun)
the lack of a relation of something to the matter at hand	the lack of a relation of something to the matter at hand