Service Manager, classic deployments, or SM, is the legacy interface for provisioning Azure resources. It was superseded by the incompatible Azure RM deployment model in 2014 as its architecture didn't scale to meet the ever-growing list of offerings available through Azure.
In SM, all resources were independent and self-contained; they couldn't reference other resources, and couldn't be grouped into resource groups. Relationships between resources for a single application had to be manually created, deleted and managed through bespoke scripts. There was also no tagging facility.
ARM vs SM support
- Cloud Services doesn't support Resource Manager.
- Virtual machines, storage accounts and virtual networks support both Resource Manager and Service Manager.
- All other services support Resource Manager.