good nature vs grace

good nature and grace both are nouns.

Word	Noun	Adjective	Verb	Adverb
good nature	Yes	No	No	No
grace	Yes	No	Yes	No

As nouns, grace is a hyponym of good nature; that is, grace is a word with a more specific, narrower meaning than good nature:

Other hyponyms of good nature include good will, goodwill, forbearance, longanimity, patience, easygoingness, risibility.

good nature (noun)	grace (noun)
a cheerful, obliging disposition	a sense of propriety and consideration for others
	elegance and beauty of movement or expression
	(Christian theology) the free and unmerited favor or beneficence of God
	a disposition to kindness and compassion
	a short prayer of thanks before a meal
	(Christian theology) a state of sanctification by God; the state of one who is under such divine influence
	a period of time past the deadline for fulfilling an obligation during which a penalty that would be imposed for being late is waived, especially an extended period granted as a special favor

good nature (verb)	grace (verb)
	make more attractive by adding ornament, colour, etc.
	be beautiful to look at