What’s the difference between an alternator and a starter?

The starter is a small motor that uses a large burst of energy from the battery to turn the engine over and start the car. The alternator, on the other hand, is your car’s electrical generator. Once the engine is running, the alternator recharges the battery and powers all of your vehicle’s electrical systems. A bad starter means your car won’t start, while a bad alternator will cause your car to die while running as the battery drains.