public vs audience

public and audience both are nouns.

Word	Noun	Adjective	Verb	Adverb
public	Yes	Yes	No	No
audience	Yes	No	No	No

public (noun)	audience (noun)
people in general considered as a whole	a conference (usually with someone important)
a body of people sharing some common interest	a gathering of spectators or listeners at a (usually public) performance
	the part of the general public interested in a source of information, entertainment, or a product/service
	an opportunity to state your case and be heard

public (adjective)	audience (adjective)
not private; open to or concerning the people as a whole
affecting the people or community as a whole