Voltage converters are also known as ‘transformers’ or ‘power converters’, and their purpose is to change a power source’s electrical output to make it useful for a particular device.
A step-down voltage transformer will come in handy when you need to ‘change’ a 220-volt power supply to a 110-volt supply. Since the US runs on 110v electrical mains,
Plug adapters or travel adapters are useful for plugging devices into wall outlets that of carrying plug shapes. They are especially handy for travelers who want to use their devices