IETF Attributes (like Service-Type or Tunnel-Private-Group-ID) are standard RADIUS attributes that every vendor (Cisco, Aruba, Juniper) must support. Vendor-Specific Attributes (VSAs) are unique (e.g., an Aruba-User-Role won't work on a Cisco switch). By using IETF attributes for common tasks like VLAN assignment, an engineer can create a single Enforcement Profile that works across all hardware in the building, significantly reducing administrative overhead.