Step 1: LPG stands for liquefied petroleum gas.
Step 2: It is a mixture of light hydrocarbons that can be liquefied under pressure.
Step 3: The major components of LPG are propane and butane, and commercial LPG commonly contains butane and isobutane.
Step 4: Methane and ethane are major components of natural gas, not LPG.
Step 5: Ethene and ethyne are unsaturated hydrocarbons and are not the main components of LPG.
\[
\boxed{\text{Butane, Isobutane}}
\]