A stainless steel rock wool sandwich panel and a standard color steel rock wool sandwich panel are both marketed as A1 fire-rated walls, yet they are fundamentally different products. One uses a 304 or 316L stainless steel skin engineered for chemical corrosion, washdown and sterile GMP environments. The other uses pre-painted galvanized steel (PE/PVDF) designed for dry, non-corrosive zones. That single difference in face material dictates the service life, maintenance cost, audit compliance and total cost of ownership (TCO) in chemical plants, food factories, laboratories and hospitals. This module defines the technical boundary between these two systems for procurement engineers, purification GCs, fire-protection subcontractors and project specifiers to prevent costly specification errors.