flash in the pan vs loser

flash in the pan and loser both are nouns.

Word	Noun	Adjective	Verb	Adverb
flash in the pan	Yes	No	No	No
loser	Yes	No	No	No

As nouns, loser is a hypernym of flash in the pan; that is, loser is a word with a broader meaning than flash in the pan:

Other hypernyms of flash in the pan include failure, nonstarter, unsuccessful person.

flash in the pan (noun)	loser (noun)
someone who enjoys transient success but then fails	a gambler who loses a bet
	a contestant who loses the contest
	a person with a record of failing; someone who loses consistently