There are three primary types of USB chargers : Cigarette Lighter USB Adapters, AC outlet to 5V USB and Portable External Battery Packs . The car USB charger adapter is often a small device that plus directly into your vehicles 12V power socket (AKA cigarette lighter port). It allows you to convert 12 Volt car battery power via the USB port to 5 Volt charging power for your smartphone. The AC to DC USB adapter plugs directly into your household 120V receptacle. The portable external battery packs, also known as USB power packs, can be used anywhere and can often be recharged via all or some of the following: AC power, cigarette lighter port, solar, or another 5V USB device.
Accordingly, there is a vast price difference between the three types and a tremendous difference in capabilities and usefulness. But nonetheless all are considered to be USB chargers. To learn more read some of our FAQs on the topic .