inundation vs spate

inundation and spate both are nouns.

Word	Noun	Adjective	Verb	Adverb
inundation	Yes	No	No	No
spate	Yes	No	No	No

As nouns, spate is a hypernym of inundation; that is, spate is a word with a broader meaning than inundation:

inundation (noun)	spate (noun)
the rising of a body of water and its overflowing onto normally dry land	the occurrence of a water flow resulting from sudden rain or melting snow
an overwhelming number or amount	a sudden forceful flow
	(often followed by `of') a large number or amount or extent