gist vs heart and soul

gist and heart and soul both are nouns.

Word	Noun	Adjective	Verb	Adverb
gist	Yes	No	No	No
heart and soul	Yes	No	No	Yes

As nouns, gist and heart and soul are synonyms defined as:

gist and heart and soul: the choicest or most essential or most vital part of some idea or experience

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

gist (noun)	heart and soul (noun)
the choicest or most essential or most vital part of some idea or experience	the choicest or most essential or most vital part of some idea or experience
the central meaning or theme of a speech or literary work

gist (adverb)	heart and soul (adverb)
	with complete faith