Although there is no difference in appearance between iphone4 and iphone4S, iphone4S is indeed better than iphone4 in hardware configuration. In fact, the configuration of the contract machine is no different from bare metal, but the purchase of the contract machine can have preferential subsidies for the return of telephone charges, which is relatively cost-effective. Only during the contract period, a phone card must be provided, otherwise the phone bill will not be refunded, and the phone may be locked. If you buy a bare machine, you only have a mobile phone, no restrictions on use, and no return of phone bills.