I think ERP is broader in scope than supply chain management, because there are potentially "resources" that the company needs that don't count as "supplies" in this scenario because they are not inputs to the primary business activity. It's all a bunch of mumbo jumbo anyway. Business practices aren't standardized, because if they were nobody would have a competitive advantage. So ERP packages have to be customized for each implementer, to a greater or lesser extent. Then when they roll out new versions you often have to roll forward all the previous customizations. It is a fiendishly efficient plan for extracting millions of predictable and annually renewable dollars from large companies. The shine is pretty much off of these large and unwieldy packages. The new focus is creating service-oriented architectures that expose business transactions in standard XML messaging formats. This allows different areas of the business to adopt the software that suits them, and expose the right pieces of it to other parts of the business and external partners.
Of course, that might turn out to be mumbo jumbo too. Never can tell.