You’re right yes. The architecture of a system is its ‘skeleton’. It’s the highest level of abstraction of a system. What kind of data storage is present, how do modules interact with each other, what recovery systems are in place. Just like design patterns, there are architectural patterns: MVC, 3-tier layered design, etc.
Software design is about designing the individual modules / components. What are the responsibilities, functions, of module x? Of class Y? What can it do, and what not? What design patterns can be used?
So in short, Software architecture is more about the design of the entire system, while software design emphasizes on module / component / class level.