hatful vs inundation

hatful and inundation both are nouns.

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

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

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

hatful (noun)	inundation (noun)
as many or as much as a hat will hold	the rising of a body of water and its overflowing onto normally dry land
(often followed by `of') a large number or amount or extent	an overwhelming number or amount