loser vs dud

loser and dud both are nouns.

Word	Noun	Adjective	Verb	Adverb
loser	Yes	No	No	No
dud	Yes	Yes	No	No

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

Other hyponyms of loser include bankrupt, insolvent, flash in the pan, flop, washout, underdog.

loser (noun)	dud (noun)
a gambler who loses a bet	an event that fails badly or is totally ineffectual
a contestant who loses the contest	an explosion that fails to occur
a person with a record of failing; someone who loses consistently	someone who is unsuccessful

loser (adjective)	dud (adjective)
	failing to detonate; especially not charged with an active explosive