Petroleum has various by products such as petrol, diesel, LPG, kerosene, CNG, etc. They are used in :
Petrol is used as fuel for cars.
Diesel is used as fuel for bigger vehicles such as trucks, buses and also trains.
CNG is compressed natural gas which is the first product obtained after refining petroleum. CNG is a comparatively cleaner fuel which is primarily used in cars or buses.
LPG stands for liquified petroleum gas. LPG is filled in a cylinder. It used to cook food.
A refined variant of kerosene is used as a fuel for aeroplanes.