I get asked this a lot of the differences between Commerce Server Standard and Enterprise. The resources on the web actually cause a few questions to be raised
Based on the MSDN site:
A) Commerce Server Application : A Commerce Server application is a logical representation of an application in Microsoft Internet Information Services (IIS); it appears in both the Commerce Server Manager and IIS console trees. In the IIS console tree, an application is either at the root directory level of the Web site or at a subdirectory level of the Web site. Web services do not count as Commerce Server applications for license purposes.
B) Commerce Server Site: A Commerce Server site includes a collection of site resources and ASP.NET-based applications that use these resources through the Commerce Server object model. With a Commerce Server site, you can administer the applications in the site as a group. Note that a Commerce Server site does not map to the concept of a Web site in IIS.
Based on these definitions, Standard Edition can have one of “A” and you can have 10 of “B” that leverages off that one “A”.