flattery vs sweet talk

flattery and sweet talk both are nouns.

Word	Noun	Adjective	Verb	Adverb
flattery	Yes	No	No	No
sweet talk	Yes	No	No	No

As nouns, sweet talk is a hyponym of flattery; that is, sweet talk is a word with a more specific, narrower meaning than flattery:

Other hyponyms of flattery include adulation, blandishment, cajolery, palaver, blarney, coaxing, soft soap, puffery.

flattery (noun)	sweet talk (noun)
excessive or insincere praise	flattery designed to gain favor