pith vs heart and soul

pith and heart and soul both are nouns.

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

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

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

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

pith (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
soft spongelike central cylinder of the stems of most flowering plants

pith (verb)	heart and soul (verb)
remove the pith from (a plant)

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