Gas engines (gasoline) burn the same fuel as most cars do although most all model planes powered with gasoline use 2 cycle engines where oil is mixed with the gasoline. Glow engines burn alcohol based fuel with an oil content added for lubrication and, in many cases also has nitromethane added to improve performance under some conditions but is not a necessary ingredient for engines properly set up to get by without it as most FAI fuels do not contain any nitromethane. Glow plugs will not work with gas as they require the catalytic action of the alcohol and glow plug element to maintain the heat necessary for combustion of the fuel.