bit part vs persona

bit part and persona both are nouns.

Word	Noun	Adjective	Verb	Adverb
bit part	Yes	No	No	No
persona	Yes	No	No	No

As nouns, persona is a hypernym of bit part; that is, persona is a word with a broader meaning than bit part:

Other hypernyms of bit part include character, part, role, theatrical role.

bit part (noun)	persona (noun)
a small role	(Jungian psychology) a personal facade that one presents to the world
	an actor's portrayal of someone in a play