A natural resource is... a material that is made in nature that no person makes. Most natural resources are made into man made resource.
A man made resource is... a material that is not made in nature, a person has to make it. Man made resources like a T-shirt can be made out of a natural resource like cotton.
1. A person can make water but water in made in nature. A person doesn't make water then dump it into the ocean, the water in made as a natural resource.
2. I use the oxygen in the air, we use oil in the car to make it move, and we use natural gas to power things we have.