rhetoric vs empty talk

rhetoric and empty talk both are nouns.

Word	Noun	Adjective	Verb	Adverb
rhetoric	Yes	No	No	No
empty talk	Yes	No	No	No

As nouns, rhetoric and empty talk are synonyms defined as:

Other synonyms of rhetoric include empty words, hot air, palaver.

rhetoric (noun)	empty talk (noun)
study of the technique and rules for using language effectively (especially in public speaking)	loud and confused and empty talk
using language effectively to please or persuade
high-flown style; excessive use of verbal ornamentation
loud and confused and empty talk