AC (alternating current) power cord plugs connect directly to the mains supply (e.g., household 220V AC) and typically feature two or three pins. They are used to deliver AC power to the internal power supply unit of an electrical appliance. Common AC plugs include the C13/C14 connectors used for computer power cords, and the C19 connectors used for rice cookers. These plugs must meet stringent safety certifications, with flame‑retardant housings and adequate clearance and creepage distances internally.

DC (direct current) power cord plugs are used in low‑voltage DC power supply scenarios, such as the common barrel connectors (e.g., 5.5mm outer diameter, 2.1mm inner diameter) found on routers, security cameras, and LED strips, as well as USB plugs (USB‑A, USB‑C, etc.). DC plugs typically operate at voltages between 5V and 48V with lower currents, and their safety requirements are less stringent than those for AC plugs. However, proper polarity matching between the plug and the device is still essential. The core differences lie in the type of current transmitted and the application scenarios. The two types must never be interchanged—never plug a DC plug directly into an AC power source, as it will instantly burn out the device.