faux pas vs blunder

faux pas and blunder both are nouns.

Word	Noun	Adjective	Verb	Adverb
faux pas	Yes	No	No	No
blunder	Yes	No	Yes	No

As nouns, blunder is a hypernym of faux pas; that is, blunder is a word with a broader meaning than faux pas:

Other hypernyms of faux pas include bloomer, blooper, boner, boo-boo, botch, bungle, flub, foul-up, fuckup, pratfall.

faux pas (noun)	blunder (noun)
a socially awkward or tactless act	an embarrassing mistake

faux pas (verb)	blunder (verb)
	utter impulsively
	make one's way clumsily or blindly
	commit a faux pas or a fault or make a serious mistake