• The structure of the system, refers to the type of architecture style (or styles)

the system is implemented in (such as microservices, layered, or microkernel).

• Architecture characteristics are another dimension of defining the success

criteria of a system, which is generally orthogonal to the functionality of the

system.

• Architecture decisions define the rules for how a system should be

constructed.

• A design principle differs from an architecture decision in that a design

principle is a guideline rather than a hard-and-fast rule.

https://learning.oreilly.com/library/view/building-evolutionary-architectures/9781491986356/ch01.html