persistency vs purpose

persistency and purpose both are nouns.

Word	Noun	Adjective	Verb	Adverb
persistency	Yes	No	No	No
purpose	Yes	No	Yes	No

As nouns, purpose is a hypernym of persistency; that is, purpose is a word with a broader meaning than persistency:

persistency: persistent determination
purpose: the quality of being determined to do or achieve something; firmness of purpose

Other hypernyms of persistency include determination.

persistency (noun)	purpose (noun)
persistent determination	what something is used for
	the quality of being determined to do or achieve something; firmness of purpose
	an anticipated outcome that is intended or that guides your planned actions

persistency (verb)	purpose (verb)
	reach a decision
	propose or intend