Petrol is a fossil fuel that is made by millions of years of decomposition dead plants and animals inside the oceans. The places where it is found are very limited. Petrol is extracted from this fossil fuel. It's a very limited resource. The more limited it is, the more fiercely it's being used by humans. That's why petrol is an exhaustible resource. On the other hand, sunlight is a source of energy which is produced by the sun by nuclear fission. In this process, a lot of energy is produced. And it's never going to end, at least until the people of earth are alive.