ARB vs RIBA — what’s the difference?

The single most misstated fact in the domain is the ARB ≠ RIBA distinction, and a verification engine must encode it. ARB (the Architects Registration Board) is the statutory regulator and keeps the legal register: ARB registration is mandatory to use the protected title “architect”. RIBA (the Royal Institute of British Architects) is a professional body, and RIBA Chartered membership is a voluntary credential on a separate roll. They are different credentials on different registers — a registered architect may or may not be RIBA Chartered, and (because regimes differ) a check against one says nothing definitive about the other. For verification: confirm ARB registration for the legal question (“is this person an architect?”), and treat RIBA Chartered as a separate, additional credential — never as a substitute for, or proof of, ARB registration.