What is the difference between butane and propane?

A gas barbecue works on butane, propane or a mixture of these two types of gas. The difference is the boiling point; the temperature at which it changes from liquid to gas and vice versa. At a lower temperature, gas becomes liquid and therefore unusable for your barbecue. With butane this boiling point is around 0°C and with propane at about -42°C. This makes Butane unusable for a winter barbecue or for use at high altitudes however, it is more affordable and more efficient than Propane.