failure vs downfall

failure and downfall both are nouns.

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

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

failure (noun)	downfall (noun)
an act that fails	a sudden decline in strength or number or importance
an unexpected omission	failure that results in a loss of position or reputation
an event that does not accomplish its intended purpose	the falling to earth of any form of water (rain or snow or hail or sleet or mist)
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