A project-buyer guide to 15 amp vs 20 amp receptacles, explaining when a 15A duplex receptacle fits a properly specified 20A multi-outlet branch circuit, when a 20A NEMA 5-20R face is required, and why grade tier often matters more than amperage for durability. Includes NEMA 5-15R vs 5-20R differences, NEC 210.21(B) context, UL 498 listing notes, and practical ordering checks for contractors, distributors, and property managers.