Human: What's the difference between natural gas and liquefied natural gas? Assistant: 
The main difference between natural gas and liquid natural gas is that natural gas is a gaseous form of energy, while LNG is a liquid form. Natural gas can be extracted from wells or produced as a by-product of petroleum refining, whereas LNG must be extracted from natural gas fields through an extremely complex process. Natural gas is typically burned in combustion engines to produce heat, whereas LNG is used as a source of energy for electricity generation, industrial processes, and transportation.