A man-made resource is a resource that has been created through the acts of humans and simply language we can say things made by man are called man made things. For example, bleach is a man-made resource. It does not exist in nature (in any significant quantity), and is produced and consumed by humans.
A natural resource is a resource that exists naturally. It might also be defined as a resource which man did not create (i.e. not man-made). For example, coal is a natural resource. It only exists in nature, and it is consumed by humans.