I think Phil correctly identified one of the main differences between polytone and aerothane.

I have done considerable auto lacquer and a little enamel (the old DULUX and some catalyzed auto urethane)

Polytone behaves much like lacquer - it is an solvent carried product that flashes off and dries quickly as the solvent goes away and does not polymerize - making it a product that has less of a tendency to run than enamels or catalyzed urethane; and, makes repairs easier because the paint can be dissolved later with solvent. Like lacquer - it takes some polishing to shine up the finished product

Aerothane behaves more like enamel, flashes off more slowly which increases the possibility of a run and it takes quite a while to fully react/harden to make a surface which is very resistant to solvent and solvent carried stains. The slow dry also makes for a shiny surface which does not need to be rubbed out.

I will admit that I have a couple of small runs in places they won't be noticed except by the guy that allowed them to happen

Left the very small run by the oil door as a reminder that I am a member of the human race when I go to fly the plane......