orator vs public speaker

orator and public speaker both are nouns.

Word	Noun	Adjective	Verb	Adverb
orator	Yes	No	No	No
public speaker	Yes	No	No	No

As nouns, orator and public speaker are synonyms defined as:

Other synonyms of orator include rhetorician, speechifier, speechmaker.

orator (noun)	public speaker (noun)
a person who delivers a speech or oration	a person who delivers a speech or oration