This is how I differentiate design and art within the time old discussion.
Design is functional. Art is expressive.
Design exists to serve a purpose, while art reflects the imagination.
Design is communicative. Art is personal.
If a design is not consumed by users, it is useless. Interfaces, posters, and furniture alike elicit targeted behavior from people, while art tends to be driven by a more personal motivation.
Design is intentional. Art is interpretational.
When someone notes that something is “created that way by design,” they mean that there is a specific goal of said element. Art is usually appreciated by the unique experience it provides its consumer, not by its effectiveness or success against metrics.
There are certainly aspects that transcend both fields, such as style, composition, and beauty. The distinction may hide under a veil of creative obscurity, but I think design at its core is considerably different from art. This breakdown of semantics is something that helps me understand and appreciate both design and art. I’d love to hear what you think about it!