flub vs fail

flub is a noun but fail is not a noun.

Word	Noun	Adjective	Verb	Adverb
flub	Yes	No	Yes	No
fail	No	No	Yes	No

As verbs, fail is a hypernym of flub; that is, fail is a word with a broader meaning than flub:

Other hypernyms of flub include go wrong, miscarry.

flub (noun)	fail (noun)
an embarrassing mistake

flub (verb)	fail (verb)
make a mess of, destroy or ruin	stop operating or functioning
	deteriorate
	prove insufficient
	disappoint, prove undependable to; abandon, forsake
	become bankrupt or insolvent; fail financially and close
	be unsuccessful
	fail to get a passing grade
	fail to do something; leave something undone
	judge unacceptable
	be unable
	fall short in what is expected