Jim--here's my shade-tree automotive engineer take. The explanation of the evolution of automotive gasoline sounds good, but the text from the Coleman site is less...illuminating. I think it's all/only in the additives. A while ago I started disposing of my old white gas in my truck gas tank. May be only due to dilution, but no knocks heard, no rough running.
Naptha is like "benzine": precise formula varies with country where spoken. I do know from working on an oil candle stove, naptha sold here is not gasoline of any kind. It burns in a wick way cleaner than diesel or gasoline (wouldn't even try) or kerosene. Painters naptha burns cleanly....and suspiciously similarly to Lamplighter Lamp Oil--just not as scented. I think Ronsonol lighter fluid is "naphtha." Charcoal lighter too, though maybe kerosene?
Thanks for Reactor update.