Iron is a natural resource. It is found in nature as Iron Ore, which is iron with oxygen and other impurities. These impurities are removed by heat treating the Iron Ore and melting away the impurities, due to different melting points of the impurities.
Steel is not a natural resource. It is a metallic alloy of iron and carbon. Iron is the natural resource and mining it has and will have many consequences on the environment. Iron will be harder and hard to mine and steel now has become one of the most recycled metals.