From InfoVis Magazine, Mary Czerwinski says
“Well, I think that [Information Architecture] is the process of distilling semantic concepts down into reasonably navigable structures, so I agree with Information architects when they say that this process has to be carried out for any website.
Then, once you have the semantic structure of the web site, you have to design it and, as a part of that information design, one needs to visualise information for the user in order for meaningful patterns of the data to “pop out” or be easily detectable.
These are very different ideas that perhaps all belong as part of one web site’s design. I’m not sure about whom is confused with regard to the three concepts, they are quite well defined and all pertain to the design of a web site.”