bang-up vs keen

bang-up is not a noun while keen is a noun.

Word	Noun	Adjective	Verb	Adverb
bang-up	No	Yes	No	No
keen	Yes	Yes	Yes	No

As adjectives, bang-up and keen are synonyms defined as:

Other synonyms of bang-up include bully, corking, cracking, dandy, great, groovy, neat, nifty, not bad, old, peachy, slap-up, smashing, swell.

bang-up (noun)	keen (noun)
	a funeral lament sung with loud wailing

bang-up (adjective)	keen (adjective)
excellent	excellent
	intense or sharp
	having or demonstrating ability to recognize or draw fine distinctions
	having a sharp cutting edge or point
	painful as if caused by a sharp instrument

bang-up (verb)	keen (verb)
	express grief verbally