neat vs slap-up

neat and slap-up both are adjectives.

Word	Noun	Adjective	Verb	Adverb
neat	No	Yes	No	No
slap-up	No	Yes	No	No

As adjectives, neat and slap-up are synonyms defined as:

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

neat (adjective)	slap-up (adjective)
free from clumsiness; precisely or deftly executed	excellent
excellent
superficially impressive, but lacking depth and attention to the true complexities of a subject
clean or organized
(of an alcoholic drink) without water
showing care in execution