poseur vs exhibitionist

poseur and exhibitionist both are nouns.

Word	Noun	Adjective	Verb	Adverb
poseur	Yes	No	No	No
exhibitionist	Yes	No	No	No

As nouns, exhibitionist is a hypernym of poseur; that is, exhibitionist is a word with a broader meaning than poseur:

poseur: a person who habitually pretends to be something he is not
exhibitionist: someone who deliberately behaves in such a way as to attract attention

Other hypernyms of poseur include show-off.

poseur (noun)	exhibitionist (noun)
a person who habitually pretends to be something he is not	someone who deliberately behaves in such a way as to attract attention
	someone with a compulsive desire to expose the genitals