From Chientai who quoted it from somewhere else:
“Art is valued for its originality and expressiveness. Its focus is on individual artifacts crafted through the manual and aesthetic virtuosity of the artist. Design, in contrast, is valued for its fitness to a particular user and task. Certainly, design is concerned with producing a life-enhancing aesthetic experience where possible, but the design aesthetic is always related to the intended function of the resulting product.”
So many times when creating commercial product we focus too much on self and not on the intended participant. It’s so incredibly simple and fundamental, yet we all too often forget this important concept.