please check this once
there are lot comparisons on windows services and web services,
*. windows services resides on windows and it are capable to start with windows startup, and
*. wcf services resides on iis level it will start after iis is started,
*. windows services are capable to controll the windows, and gives/ controls the soft ware which running on windows
*. wcf services are capable to give/ control the windows or web applications.
*. windows services are capable on tcp-protocol
*. wcf services are capable of HTTP-protocol.
*. windows services mainly useful when we want to run a software without manual interaction to process it for the selected operations.
*. wcf services are useful when we want a faster data access for our application to give effective results in effective manner.