show-off vs poseur

show-off and poseur both are nouns.

Word	Noun	Adjective	Verb	Adverb
show-off	Yes	No	No	No
poseur	Yes	No	No	No

As nouns, poseur is a hyponym of show-off; that is, poseur is a word with a more specific, narrower meaning than show-off:

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

Other hyponyms of show-off include grandstander, hot dog, hotdog, poser.

show-off (noun)	poseur (noun)
someone who deliberately behaves in such a way as to attract attention	a person who habitually pretends to be something he is not