great vs smashing

great and smashing both are nouns.

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

As adjectives, great and smashing are synonyms defined as:

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

great (noun)	smashing (noun)
a person who has achieved distinction and honor in some field	the act of breaking something into small pieces

great (adjective)	smashing (adjective)
excellent	excellent
in an advanced stage of pregnancy
uppercase
remarkable or out of the ordinary in degree or magnitude or effect
of major significance or importance
relatively large in size or number or extent; larger than others of its kind