The document-wrapped adds one "wrapper" element around parameters (so request looks like valid XML and can be valiadted against schemas). RPC-style also has operation name as parent element (i.e. wrapping element) for method parameters elements. So, you won't notice any difference looking at SOAP request for document-wrapped and RPC style web service.
You can notice difference if you compare RPS style with bare document style. In this case document style won't have operation name in SOAP message.
You can find out difference between document-wrapped and RPC by looking at WSDL