inwardness vs nitty-gritty

inwardness and nitty-gritty both are nouns.

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

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

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

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

inwardness (noun)	nitty-gritty (noun)
the quality or state of being inward or internal	the choicest or most essential or most vital part of some idea or experience
preoccupation with what concerns human inner nature (especially ethical or ideological values)
preoccupation especially with one's attitudes and ethical or ideological values
the choicest or most essential or most vital part of some idea or experience