nitty-gritty vs sum

nitty-gritty and sum both are nouns.

Word	Noun	Adjective	Verb	Adverb
nitty-gritty	Yes	No	No	No
sum	Yes	No	Yes	No

As nouns, nitty-gritty and sum are synonyms defined as:

nitty-gritty and sum: the choicest or most essential or most vital part of some idea or experience

Other synonyms of nitty-gritty include center, centre, core, essence, gist, heart, heart and soul, inwardness, kernel, marrow, meat, nub, pith, substance.

nitty-gritty (noun)	sum (noun)
the choicest or most essential or most vital part of some idea or experience	the whole amount
	the choicest or most essential or most vital part of some idea or experience
	a quantity obtained by the addition of a group of numbers
	the final aggregate
	a set containing all and only the members of two or more given sets
	a quantity of money

nitty-gritty (verb)	sum (verb)
	determine the sum of
	be a summary of