Why one or the other when it comes to small parts with spray paint? What the method preparation method. Lacquer clearly doesn't case for moisture.
Lacquer dries faster, is more susceptible to shrinking and cracking with age, and chips easier. Enamel takes a long time to fully dry and remains a little soft, therefore it is more impact resistant.
Lacquer requires a lacquer based primer so it has something to bite into and bond properly. Lacquer can't be painter over bare metal, enamel can. Lacquer bonds chemically/covaliently, enamel bonds mechanically which meant the surface must be properly abraded. Many spray cans with enamel use lacquer thinner as a transferring agent so it dries faster. The down side of doing this is if you wait more then a couple hours to put more coats on, the previous coat will lift or alligator. I ran into this problem with Eastwood chassis paint when I waited over night to put my second coat on.
Lacquer works great on ABS plastics like grills and consoles with no primer at all. On polyprolene plastics like kick panels and bucket seat parts you need an adhesion promoter like Bulldog or SEM clear. Let the promoter barely dry then paint and it takes nice.
