In a nutshell, an adapter takes one voltage and converts it to another (often lower) voltage (often changing it from AC to DC in the process). A charger takes a given voltage and uses it to charge a battery. In terms of power input and output they are the same. A travel adapter is usually made smaller for portability.

The terms "adapter" and "travel adapter" are often used interchangeably to describe a device that allows a plug from one country to fit into the wall outlet of another. Technically, an adapter is any device that joins two incompatible parts, while a travel adapter specifically refers to a plug-interface converter used for international electricity. However, the most critical distinction for travelers is between an adapter and a converter. An adapter only changes the physical shape of the plug so it can enter the socket; it does not change the voltage. A voltage converter (or transformer), on the other hand, actually changes the electrical output (e.g., from 220V to 110V). If you use a simple adapter for a single-voltage device like an American hair dryer in Europe, the device will likely fry because the voltage is too high. Most modern electronics like phones and laptops are "dual-voltage" (100-240V) and only need a basic travel adapter. Always check your device's "Input" label to see if it requires just a physical plug change or a full voltage conversion.