spate vs inundation

spate and inundation both are nouns.

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

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

Other hyponyms of spate include deluge, flood, torrent, haymow.

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