smarten up vs spiff up

smarten up and spiff up both are verbs.

Word	Noun	Adjective	Verb	Adverb
smarten up	No	No	Yes	No
spiff up	No	No	Yes	No

As verbs, smarten up and spiff up are synonyms defined as:

Other synonyms of smarten up include slick up, spruce, spruce up, titivate, tittivate.

smarten up (verb)	spiff up (verb)
dress and groom with particular care, as for a special occasion	make neat, smart, or trim
make neat, smart, or trim