Throughout my career as a practitioner and teacher of cloud architecture and general enterprise architecture, I’ve focused on the distinction between logical and physical architectures.
It’s no secret what they comprise: A logical architecture is a structure of technology concepts that does not name specific technologies or brands, while a physical architecture does contain specific technologies and brands.
When I design a cloud computing architecture, I first ask what problems need to be solved. I then determine what an acceptable solution will require. Next, I list the items that need to be part of the architecture and their relationships to each other: databases, middleware, encryption, storage, compute, application development, etc. Again, no specific technologies, only technological concepts that can contribute to solving the overall problems.