The professional disciplines involved and their respective knowledge bases and 'political' influence. The location of staff - their physical base. Where they actually work - context. Their role and others expectations of their role. It is these sources of fuzziness and many others besides that frequently 'trip us up' when it comes to understanding our information use and support via ICT solutions.
Situations can be complex, but they can be straightforward to understand.
Of course, it is never as straightforward as this. The distinctions made above may appear to be quite exclusive, but they are not. For example, the items listed in types of interchange can also be thought of as forms of communication, or examples of media. This is one subtlety, but there are many others. We can also try to take a page from the astrophysicist's book.