I doubt store bought Sterno has Diesel or a fuel oil base to it. Sterno is used indoors for heating those catering and buffet pans you see at parties and such. If they contained Diesel they would smoke and stink like hell. I think, (I say "think" because I'm not sure), commercial Sterno uses some type of alcohol blend that burns smoke free and odorless. If you tried to make homemade NAPALM with Kerosene or Diesel, I don't think it would attack and melt the Styrofoam, because Diesel and Kerosene doesn't attack plastic the way gasoline does.
K-1 grade Kerosene will burn far cleaner than Diesel because it has far less Paraffin in it. K-1 Kerosene is also the base product for Jet-A jet fuel. They changed the formula from JP-4 to help reduce jet engines smoking at full power settings.