breakdown vs failure

breakdown and failure both are nouns.

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

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

breakdown (noun)	failure (noun)
the act of disrupting an established order so it fails to continue	an act that fails
an analysis into mutually exclusive categories	an unexpected omission
a cessation of normal operation	an event that does not accomplish its intended purpose
(biology) the process of decay caused by bacterial or fungal action	a person with a record of failing; someone who loses consistently
(chemistry) separation of a substance into two or more substances that may differ from each other and from the original substance	lack of success
a mental or physical breakdown	loss of ability to function normally
	inability to discharge all your debts as they come due