scoundrel vs persona non grata

scoundrel and persona non grata both are nouns.

Word	Noun	Adjective	Verb	Adverb
scoundrel	Yes	No	No	No
persona non grata	Yes	No	No	No

As nouns, persona non grata is a hypernym of scoundrel; that is, persona non grata is a word with a broader meaning than scoundrel:

Other hypernyms of scoundrel include unwelcome person.

scoundrel (noun)	persona non grata (noun)
a wicked or evil person; someone who does evil deliberately	a person who for some reason is not wanted or welcome
	a diplomat who is unacceptable to the government to which he is sent