• Petrol and diesel engines ignite their fuel in different ways, so the fuels they use have to be designed differently too. Petrol engines use an electric spark to ignite a compressed mix of petrol and air.
• Diesel engines squeeze fuel and air so tightly that the mixture self-ignites without the need for an electric spark. Diesel engines are more efficient because of their greater compression compared with petrol engines, allowing them to make better use of the heat generated.
• Petrol is made of shorter chain molecules and contains less energy per litre. Diesel is made of components with longer molecular chains and contains more energy per litre.

Watch video below which explains the difference between Petrol and Diesel