In short, Warehousing is part of Supply Chain Management. Where Supply Chain Management look at the entire supply chain, from raw material to end product, warehousing only looks at handling goods in the warehouse. Many supply chains will have warehousing in their process, often several. You can think of raw material storage, subparts, and eventually the finished product and distribution warehouses.
But, there could also be supply chains that do not have warehousing, where it would be either too expensive or even impossible. A good example would be the distribution of water.