spiffed up vs dressed

spiffed up and dressed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
spiffed up	No	Yes	No	No
dressed	No	Yes	No	No

As adjectives, spiffed up and dressed are synonyms defined as:

Other synonyms of spiffed up include dolled up, dressed-up, dressed to kill, dressed to the nines, spruced up, togged up.

spiffed up (adjective)	dressed (adjective)
dressed in fancy or formal clothing	dressed or clothed especially in fine attire; often used in combination
	(of lumber or stone) to trim and smooth
	treated with medications and protective covering
	dressed in fancy or formal clothing