flashflood vs deluge

flashflood and deluge both are nouns.

Word	Noun	Adjective	Verb	Adverb
flashflood	Yes	No	No	No
deluge	Yes	No	Yes	No

As nouns, deluge is a hypernym of flashflood; that is, deluge is a word with a broader meaning than flashflood:

flashflood: a sudden local flood of great volume and short duration
deluge: the rising of a body of water and its overflowing onto normally dry land

Other hypernyms of flashflood include alluvion, flood, inundation.

flashflood (noun)	deluge (noun)
a sudden local flood of great volume and short duration	a heavy rain
	the rising of a body of water and its overflowing onto normally dry land
	an overwhelming number or amount

flashflood (verb)	deluge (verb)
	fill or cover completely, usually with water
	charge someone with too many tasks
	fill quickly beyond capacity; as with a liquid