What is compressed natural gas, liquefied natural gas, and liquefied petroleum gas?

"Compressed natural gas" means natural gas that has been compressed and is advertised, offered for sale, suitable for use, sold, or used as an engine motor fuel. "Liquefied natural gas" means natural gas that has been cooled to a liquid state and is advertised, offered for sale, sold, suitable for use, or used as an engine motor fuel. "Liquefied petroleum gas" means the gas derived from petroleum or natural gas which is in a gaseous state at normal atmospheric temperature and pressure and maintained in the liquid state at normal atmospheric temperature by means of suitable pressure and which is dispensed into motor fuel storage containers and is advertised, offered for sale, sold, suitable for use, or used as an engine motor fuel. The term "liquefied petroleum gas" or "LPG" refers to propane.