warning vs threat

warning and threat both are nouns.

Word	Noun	Adjective	Verb	Adverb
warning	Yes	Yes	No	No
threat	Yes	No	No	No

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

warning (noun)	threat (noun)
a message informing of danger	a warning that something unpleasant is imminent
cautionary advice about something imminent (especially imminent danger or other unpleasantness)	declaration of an intention or a determination to inflict harm on another
notification of something, usually in advance	a person who inspires fear or dread
	something that is a source of danger

warning (adjective)	threat (adjective)
serving to warn