bighearted vs giving

bighearted is not a noun while giving is a noun.

Word	Noun	Adjective	Verb	Adverb
bighearted	No	Yes	No	No
giving	Yes	Yes	No	No

As adjectives, bighearted and giving are synonyms defined as:

Other synonyms of bighearted include big, bounteous, bountiful, freehanded, handsome, liberal, openhanded.

bighearted (noun)	giving (noun)
	the act of giving
	disposing of property by voluntary transfer without receiving value in return
	the imparting of news or promises etc.

bighearted (adjective)	giving (adjective)
given or giving freely	given or giving freely