There is a common public misunderstanding that propane and natural gas are the same thing. This misunderstanding can be attributed to the number of apparent similarities between the two gases. Both can transported by tank truck, are colorless and odorless (in pure form), and are often put to the same residential uses (heating, cooking and in grills). However, there are number of differences between the two gases that are discussed below.
Weight
Natural gas is about the same weight as air and will disperse throughout air. Propane is heavier than air and will accumulate near the floor rather than dispersing.
Industrial Uses
Even though both are used as vehicle fuels, propane is also used in an industrial refrigeration technique called gas absorption refrigeration, in the production of petrochemicals, semiconductors and in the production of propyl alcohol. Natural gas is used industrially in power plants and for the production of fabrics, paints and glass.
Weapons
Propane has been used in the past, and occasionally in the present, in flamethrowers. Natural gas is not typically used in this fashion.
Sources
While natural gas, which is mostly methane, occurs normally in nature, propane is a byproduct of the refining process of either natural gas or oil.
Economics
Liquid natural gas is generally considered to be less economical than liquid propane and, therefore, is less popular in rural areas where gas must be trucked to individual, residential storage tanks.