ResourceGroup VS. WebSpace

Though both are used to group related Azure resources together, they are quite distinct. WebSpace is a pre-AzureResourceManager (ARM) concept how one would group Azure resources together. An Azure resource (eg. AppService, AppServicePlan) can belong to only one WebSpace and one ResourceGroup. In general, multiple Azure resources in the same ResourceGroup will also belong to the same WebSpace.

Azure Resources can be moved from one to another ResourceGroup. However, they will always be in their origin WebSpaces; think of this as theirs physical present (content, data, etc.). They can NOT be moved from one WebSpace to another without explicit delete and recreate by owners. As a result, it is not uncommon that multiple resources in the same WebSpace can belong to different ResourceGroups and vice versa.

To see what WebSpace an AppService belongs to, open Azure Resource Explorer and navigate to the specific AppService. The WebSpace information is available via SelfLink property.

All AppServices in the same AppServicePlan belong to the same WebSpace as AppServicePlan's.