nonstarter vs dud

nonstarter and dud both are nouns.

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

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

nonstarter: a person with a record of failing; someone who loses consistently
dud: someone who is unsuccessful

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

nonstarter (noun)	dud (noun)
a horse that fails to run in a race for which it has been entered	an event that fails badly or is totally ineffectual
a person with a record of failing; someone who loses consistently	an explosion that fails to occur
	someone who is unsuccessful

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