The architectural design describes the underlying structure of the entire software product. It contains those facts and interfaces individual developers must know so that their code works correctly within the product. It does not describe the user interface. It may or may not describe interfaces to other products, hardware or software. Microsoft Secrets , by Cusumano and Selby, describes an architecture whose goal is to allow features to be added or modified independently of each other.
Architectural design means creating interfaces.
Writing Solid Code , by Steve Maguire, has a good discussion of designing interfaces that are less likely to be misused. Crossing the Chasm and Inside the Tornado , by Geoffrey Moore, discuss how the focus of the product changes over its life cycle. Ideally, the architectural design would support those changes. Note that the books are mainly about product marketing, so the information about design is scattered thinly throughout them. Rapid Development , by Steve McConnell, has a brief and conventional chapter on Designing for Change.