Both mobility scooters and power wheelchairs may be used indoors and outdoors, but power wheelchairs are generally for indoor use and mobility scooters for outdoor use. Mobility scooters are controlled by tillers, whereas most power wheelchairs are controlled by joysticks. People who use mobility scooters must be able to sit upright for long periods of time. If that is not possible, power wheelchairs are a better choice since the seats offer more support.