profanity vs dirty word

profanity and dirty word both are nouns.

Word	Noun	Adjective	Verb	Adverb
profanity	Yes	No	No	No
dirty word	Yes	No	No	No

As nouns, dirty word is a hyponym of profanity; that is, dirty word is a word with a more specific, narrower meaning than profanity:

Other hyponyms of profanity include blasphemy, filth, obscenity, smut, vulgarism, curse, curse word, cuss, expletive, oath, swearing, swearword.

profanity (noun)	dirty word (noun)
vulgar or irreverent speech or action	an offensive or indecent word or phrase
	a word that is considered to be unmentionable