ass-kisser vs flatterer

ass-kisser and flatterer both are nouns.

Word	Noun	Adjective	Verb	Adverb
ass-kisser	Yes	No	No	No
flatterer	Yes	No	No	No

As nouns, flatterer is a hypernym of ass-kisser; that is, flatterer is a word with a broader meaning than ass-kisser:

ass-kisser: a person who tries to please someone in order to gain a personal advantage
flatterer: a person who uses flattery

Other hypernyms of ass-kisser include adulator.

ass-kisser (noun)	flatterer (noun)
a person who tries to please someone in order to gain a personal advantage	a person who uses flattery