relevancy vs pertinency

relevancy and pertinency both are nouns.

Word	Noun	Adjective	Verb	Adverb
relevancy	Yes	No	No	No
pertinency	Yes	No	No	No

As nouns, pertinency is a hyponym of relevancy; that is, pertinency is a word with a more specific, narrower meaning than relevancy:

Other hyponyms of relevancy include materiality, cogency, point, applicability, pertinence.

relevancy (noun)	pertinency (noun)
the relation of something to the matter at hand	relevance by virtue of being applicable to the matter at hand