What core competencies differentiate a User Experience Designer from an Information Architect?
UX covers more than just IA. As I learned from Matt, UX = IA + Accessibility + Usability + IxD.
While - as others have pointed out - there are certainly theoretical differences in how people perceive the two job titles.
However, in practice, you'll find that many of the people with an IA title are in fact doing a great deal of more general UX work.
So the real answer is "it depends" :-)
Jesse James Garret, author of "The Elements of User Experience", made an infamous visualization on User Experience elements before writing his book. It has two different scales: Abstract to Concrete- scale and Conception to Completion-scale. It's divided into five layers which should be read from the bottom and upward (from Conception to Completion and from Abstract to Concrete over time).
Download the original PDF from March 30, 2000.
It reflects the process of designing any artifact from a User Experience perspective. Garret highlights what is important at each layer and each stage of the project. Beware though, this image should not be seen as a project roadmap where you complete one layer before moving on to the next. Garret states though that you can't finish one layer before preceding layers are finished. You need to be agile and move between layers as you move along.
It is possible to transfer these layers into different competencies. The User Experience Designer cover all of these aspects of the visualization:
The Information Architect (IA) is a more specialized area of User Experience. In short an Information Architect "connects people to the content they're looking for". To do this the IA have four different tools:
Image by murdocke23 on Flickr
That's the difference between a User Experience Designer and an Information Architect.
Information Architecture (IA) is one aspect of User Experience (UX).
Information Architecture relates to the problems of structuring large amounts of information:
So the key text on this is 'The Polar Bear Book'
Co authored by Louise Rosenfeld.
Whose professional background was library science.
As a graduate student in library and information studies in the late 1980s, Lou became convinced that the skills of librarians were grossly undervalued — in the coming information explosion, who else would supply the skills of organizing, classifying and labeling information?
As the Web sped that explosion along, Lou realized that additional skills and perspectives were required to develop coherent, intuitive structures — information architectures — that made web content accessible to users.
So IA is the application of library science to the overall UX mix.
IA is particularly relevant in situations where there is a lot of information, such as corporate intranets.