Information Architecture is Not Usability
http://www.digital-web.com/articles/information_architecture_is_not_usability/

Lash, Jeff
Digital Web Magazine
2002

Abstract:

The distinction between information architecture and usability may seem like semantics, but there are significant differences between the two disciplines. Though they are often discussed interchangeably, and practitioners are often well-versed in both, information architecture and usability differ in their scope and areas of focus.