great vs dandy

great and dandy both are nouns.

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

As adjectives, great and dandy are synonyms defined as:

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

great (noun)	dandy (noun)
a person who has achieved distinction and honor in some field	a sailing vessel with two masts; a small mizzen is aft of the rudderpost
	a man who is much concerned with his dress and appearance

great (adjective)	dandy (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