You meant difference b/w test.aspx?wsdl and anothertest.wsdl???
Ok generally test.aspx?wsdl is a dynamically generated WSDL, so this WSDL might have been generated based on the Code. May be code first approach based WSDL. So lets say you add a new method in you code at a later point after recompilation the WSDL will be updated to show the new operation.
anothertest.wsdl is a static WSDL, so this is like a Contract First approach (may be there are some exceptions not sure). So its like the implementation of this service will always have the exact operations mentioned in this WSDL. if any updates done to the implementation may not reflect the WSDL hence those enhancements can't be exposed to the external world until you manually update the WSDL.
