Coke is obtained by the destructive distillation of coal. It is carried out by heating coal strongly to 1000°C in the absence of air. Coke is an almost pure form of carbon. It is a good fuel and burns with no smoke. It is also used to reduce metal oxides, such as iron and zinc oxides, to get the metals.

Petroleum is a naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface. It is commonly refined into various types of fuels like petrol, diesel etc.

The crude oil is not a single chemical compound. It is a complex mixture of several solid, liquid and gaseous hydrocarbons. Petroleum is the crude oil from which the fuels like LPG, diesel, kerosene and petrol are obtained.