downfall vs failure

downfall and failure both are nouns.

Word	Noun	Adjective	Verb	Adverb
downfall	Yes	No	No	No
failure	Yes	No	No	No

As nouns, failure is a hypernym of downfall; that is, failure is a word with a broader meaning than downfall:

downfall (noun)	failure (noun)
a sudden decline in strength or number or importance	an act that fails
failure that results in a loss of position or reputation	an unexpected omission
the falling to earth of any form of water (rain or snow or hail or sleet or mist)	an event that does not accomplish its intended purpose
	a person with a record of failing; someone who loses consistently
	lack of success
	loss of ability to function normally
	inability to discharge all your debts as they come due