slew vs great deal

slew and great deal both are nouns.

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

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

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

slew (noun)	great deal (noun)
(often followed by `of') a large number or amount or extent	(often followed by `of') a large number or amount or extent

slew (verb)	great deal (verb)
turn sharply; change direction abruptly
move obliquely or sideways, usually in an uncontrolled manner