Service addresses and billing addresses are necessary to have a service through providers like Internet, cable, or phones. A service address is where the service will be used. It is vital to provide the correct service address for things like the Internet and cable because that is where those services would be installed.
The billing address is associated with the card used during payment. This address is registered with the card provider and must match with that the provider has so that the payment will go through. Though service and billing addresses are different, the user can have the same address for both.