Man-made and Not existing in nature

Man-made adjective - Being such in appearance only and made with or manufactured from usually cheaper materials.

Not existing in nature and man-made are semantically related. In some cases you can use "Not existing in nature" instead an adjective phrase "Man-made".

Man-made and not existing in nature are semantically related. You can use "Man-made" instead an adjective phrase "Not existing in nature".