peachy vs smashing

peachy is not a noun while smashing is a noun.

Word	Noun	Adjective	Verb	Adverb
peachy	No	Yes	No	No
smashing	Yes	Yes	No	No

As adjectives, peachy and smashing are synonyms defined as:

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

peachy (noun)	smashing (noun)
	the act of breaking something into small pieces

peachy (adjective)	smashing (adjective)
of something resembling a peach in color	excellent
excellent