A power supply delivers electrical power to operate a device continuously, while a charger stores energy into a rechargeable battery for later use. The key distinction lies in their intended purpose and output behavior.
A power supply is designed to convert AC mains electricity into regulated DC power that directly feeds a device's components. It provides continuous voltage and current, allowing the device to function while plugged in. Power supplies are found in desktop computers, monitors, microwave ovens, and other appliances that need constant power. They typically don't involve energy storage—they simply transform and regulate incoming electricity.
A charger, by contrast, is specifically designed to transfer electrical energy into a rechargeable battery. It includes circuitry that manages the charging process, typically regulating current and voltage to prevent battery damage. Chargers are used for phones, laptops, cameras, and other portable devices with built-in batteries. Once charging completes, the device can operate independently from wall power.
There is overlap in modern devices: many laptop chargers function as power supplies when the device is plugged in (powering the system directly) while simultaneously charging the battery. Similarly, some devices use external power supplies that include charging functionality. The distinction depends on whether the primary role is delivering operational power or storing energy in a battery. In essence, a power supply is about delivery of electricity to run something now, while a charger is about storing electricity for use later.