[edited version of post I made on Dr. Dobbs Portal]

Back in April I  provided a definition for "architecture" as one of my first posts on DDJ. I also promised I'll talk about the distinction betwen Architecture and Design. Well this time is now.

When I try to think about it. I see two base criteria to distinguish between the architecture and design:

• Design deals with local decisions, where architecture is broader. For instance, you "design" the interfaces for your classes, but you "architect" the division into tiers.
• Design is mostly about the functional requirements, while architecture is mostly about quality attributes. You design how a specific workflow will fulfill a certain use case, but you architect the solution to the system's availability.

It is probably quite evident that this distinction only provides blurry borders between architecture and design; for example, when you have a multi-tier solution and you "architect" the UI and say it will implement MVP pattern. Can this be considered local decision and thus design or is this the overall decision (for the UI) and thus architecture?

The way I see it the exact cross-point from architecture to design is not that important. The point in talking about two distinct activities in the development process is to maintain separation of concern. you need to handle both to make sure a solution will actually work whether you do a little design while architecting or do a little architecture while designing really doesn't matter. Also architects should be involved in both activities anyway...