Service Reference Proxy method Generation

I have two Biztalk applications, each of which expose a webservice port, I'm consuming them in an ASP.NET client using the 'Add service reference' tool from within the VS2010 GUI to generate the proxies.

But the proxy interface is s开发者_如何学编程lightly different in both. One takes two parameters, returns the 'response' via a parameter using the out keyword and has a void return type,

the other takes one parameter and returns the response using a typed return value.

I'm confused as to what is causing the difference in behavior, is something I'm doing as part of the creation of the references (as far as I can tell I've used the same process) or is it something about the server/WSDL I'm consuming?

EDIT -As per Grahams comment the type of proxy interface generated seems to depend on whether there is a namespace or not. I'll give the answer to whoever can put together the clearest description of what exactly is happening there.

As noted in the comments, the inclusing of a namespace in one of the services is what was triggering the difference in the proxy code generation. It's still not clear exactly why this is the case however.