The difference between propane, or liquid petroleum gas (LPG), and natural gas comes down to their portability, compression, energy efficiency, and cost. However, there is generally no difference when it comes to performance in appliances for heating, cooking, or drying. The mixture of natural gas is comprised of propane, along with other gases like methane, butane, ethane, and pentane.

One difference in the physical properties of propane and natural gas is how easily they liquefy and transport. Propane turns into a liquid at —46° F (-43° C), so it's easy to compress and carry in a portable tank. You can buy compressed propane at most gas stations. It's decompressed by a valve at the source of use, such as a barbeque grill. Yet natural gas doesn't compress as easily. It usually comes to your home from a utility company along dedicated lines to power things like a central heating system, clothes dryer, and water heater.

Propane is heavier than air which is heavier than natural gas. Both natural gas and propane will dissipate into the air if they are released in an open enough environment and both can pose an explosive risk if they concentrate enough and are ignited. However, because propane is heavier, it tends to fall to the ground, collect, and pose a greater explosive risk. On the other hand, because natural gas is lighter than air, it tends to rise and dissipate into the air, posing less of an explosive risk.

Propane provides more energy per unit volume than does natural gas. Heat is measured in BTUs, or British Thermal Units. Propane provides about 2500 BTUs for the same volume of natural gas that only gives 1000 BTUs. However, natural gas can be less expensive at up to one-sixth the cost of propane, depending on where you live. Utilities in colder climates might supply natural gas for less money, especially during winter months. Some rural areas don't have access to a utility company that provides gas service.

Since they are both petroleum distillates, made of hydrocarbons, these gases have comparable power. Natural gas, as its name implies, develops naturally in deposits underground, so it only needs to be pumped out to use. Propane, since it is one of the gases in those deposits, must be further separated and distilled.

You probably couldn't tell the difference between their performance on a grill or water heater. They ignite at the same temperature. Some barbecue enthusiasts prefer natural gas because it is a cleaner burning fuel, which means it doesn't release as many pollutants into the air. Exhaust from propane might affect the taste of food. To the end user, there aren't many differences between natural gas and propane, but they do differ in their chemical properties.