Our readingWhat is a korrent?
Even when a product manager can contribute to prototypes, the designer is still doing something specific to a designer's role.
Drawn from what Luis Ouriach said
What these subjects mean
design How things should be made and judged: what makes a design good, who should do the designing, and what an interface is for.
product management What a product manager is for, who decides what gets built, and what happens to that job once delivery is cheap.