Naptha is actually one of the low-octane components of gasoline. That's why you generally don't want to use naphtha/lighter fluid/coleman stove fuel (which are all naptha based) in your vehicle, as it will lower the octane and potentially cause detonation. IIRC, fuel for camp stoves is around 50 RON (the octane scale), whereas gasoline for automobiles is typical in the 80's+.

With that said, there are other differences between the products, that can effect interchangeability. I'm not a chemist, so I can't tell you which are safe to use. The question that I answered was simply, where would one find a source of naphtha?

IIRC, Blast works as a chemist in the petro-chemical industry. He would probably be able to confirm whether or not one could safely use painter's naphtha in a liquid fuel camp stove.

Gasoline/petrol stoves

If your stove is a gasoline stove, use white gasoline, Coleman Fuel, heptanes and similar as a first choice. In some countries ‘unleaded environmental gasoline is available and can be used as a second choice. Unleaded environmental gasoline is not the same as unleaded car gasoline. Environmental unleaded gasoline is a fuel designed for garden machines (i.e. lawn mowers) with four-stroke engines. It does not contain benzene and many of the other health hazardous additives that are put into car gasoline. Unleaded car gasoline contains a lot of additives that are needed for smooth engine operation etc, but these additives are extremely health hazardous and they are not burnt off properly when used in a stove. Instead, they escape as hazardous fuel vapour and exhaust fumes. Therefore, never use car gasoline of any kind for your stove!