How to select sitemap from many (asp.net)

The problem looks somewhat artificial to me. I would not separate admin and user pages at all. And the sitemap is sitemap, by its idea, it should show all the contents. This is not a flexible design. What if you introduce yes another user's role, what are you going to do?

In my opinion, the most natural approach would be this: you design unified pages for all users. (Of course, some users will never get links to some pages, but you should not rely on it: you should assume that any user will try to navigate to any page by directly typing any URI.) For any page, you can generate only the subset of the content, depending on the current user. This approach can be used event if the contents for the user and admin look entirely different: you still can have, say, student part and admin part separately, and generate only the one part per HTTP request, depending on the role.

Just one of the possible ideas. I do understand that the convenience and supportability of each design depends on the specific features of concrete content.

—SA