In most successful software project, the expert developer working on the project have a shared understanding of the system design. The shared system design is called "Architecture". The shared understanding includes how the system is divided into components and how those components interacts through interfaces. Those components are usually composed of small components, but the architecture only includes those components and interfaces that understandable by all developers. Architecture is about important stuff, whatever is.
All architecture are design, but not all design is architecture. Architecture represents the significant design decision that shapes a system where significant is measured by the cost of change.
The goal of architecture is eliminate the impact and cost of change.
Making everything easy to change makes the entire system complex.