Battery electric vehicles (BEV) are powered completely by a rechargeable battery so you'll never need a drop of gas or an oil change. All you have to do is plug in, recharge, and go.
Hybrid Electric Vehicles (HEV) use battery and gas to optimize fuel efficiency and performance. They don't need to be plugged in as regenerative braking and the gas engine recharge the battery pack.
Plug-in hybrid electric vehicles (PHEV) are also powered by both battery and gas, using the battery first and switching to gas once the battery is depleted, giving you the best of both worlds.