great deal vs spate

great deal and spate both are nouns.

Word	Noun	Adjective	Verb	Adverb
great deal	Yes	No	No	No
spate	Yes	No	No	No

As nouns, great deal and spate are synonyms defined as:

great deal and spate: (often followed by `of') a large number or amount or extent

great deal (noun)	spate (noun)
(often followed by `of') a large number or amount or extent	the occurrence of a water flow resulting from sudden rain or melting snow
	a sudden forceful flow
	(often followed by `of') a large number or amount or extent