as above, propane is designed to be used outside.
butane doesn’t work well at low temperatures. When too cool it stays as a liquid and the gas pressure drops. That means a butane gas cylinder will produce lower pressure once the bottle temperature drops below 10 degrees C.
They have similar properties but different applications. They are not interchangeable due to the different operating pressures and burner settings required. Valves and fittings are also different to avoid confusion or accidental use of the wrong type of LPG.
Propane has a lower boiling point than butane so it will continue to convert from a liquid to a gas even in very cold conditions, down to -45ºC. When stored as a liquid in a tank, it exerts a greater pressure than Butane at the same temperature.
So Propane, as an LPG, is most suitable for exterior storage and use. Its ability to operate in low temperatures makes it the most suitable LPG for many applications. Propane is widely used as a fuel source for domestic and commercial heating, hot water and cooking. It also has a wide range of uses in industry and agriculture.
Butane has the lower vapour pressure at equivalent temperatures and is suitable for interior use or outside during the summer. Butane is a very common fuel amongst leisure users and owners of portable heaters.