blackmail vs extortion

blackmail and extortion both are nouns.

Word	Noun	Adjective	Verb	Adverb
blackmail	Yes	No	Yes	No
extortion	Yes	No	No	No

As nouns, extortion is a hypernym of blackmail; that is, extortion is a word with a broader meaning than blackmail:

blackmail: extortion of money by threats to divulge discrediting information
extortion: the felonious act of extorting money (as by threats of violence)

blackmail (noun)	extortion (noun)
extortion of money by threats to divulge discrediting information	the felonious act of extorting money (as by threats of violence)
	unjust exaction (as by the misuse of authority)
	an exorbitant charge

blackmail (verb)	extortion (verb)
obtain through threats
exert pressure on someone through threats