muff vs flub

muff and flub both are nouns.

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

As nouns, flub is a hypernym of muff; that is, flub is a word with a broader meaning than muff:

Other hypernyms of muff include bloomer, blooper, blunder, boner, boo-boo, botch, bungle, foul-up, fuckup, pratfall.

As verbs, muff and flub are synonyms defined as:

muff (noun)	flub (noun)
(sports) dropping the ball	an embarrassing mistake
a warm tubular covering for the hands

muff (verb)	flub (verb)
make a mess of, destroy or ruin	make a mess of, destroy or ruin
fail to catch, as of a ball