1. The Architecture-Engineering Process is distinct from the larger Systems-Engineering Process in that it is focused on design Issues. (Systems-Engineering is broader. It includes consideration of the Requirements, Quality-Control, project management, and any other discipline, that is useful for satisfying Requirements.)
2. The Architecture-Engineering Process is distinct from the other system Level Design-Engineering Processes because it operates at a higher Level, and is therefore concerned with wider Issues. It has to consider the overall strategic framework, and provide guidance to all the lower-Level systems.
The Architecture-Engineering Process considers especially the long-term objectives, and the totality of the Requirements for all systems.
3. The Architecture-Engineering Process is, ideally, technologically neutral. It should provide guidance on design, using any relevant technology, Policy, motivation, organizational Idea, contractual agreement, sales practice and other devices. One of the main criteria is that the Architecture is cost-effective.
Technological neutrality is not always achieved! For example, promotion of the use of Standard platforms could be included within a Systems-Architecture; and while that is an architectural decision, it is not technologically neutral.