Walking and running shoes look nearly identical. However, they have some key differences that make them better for their respective activities. The sole of a walking shoe is usually stiffer since the foot doesn’t have to flex as much while walking. If there’s too much flexibility in a walking shoe, it can fatigue the foot faster because the muscles in the foot have to work harder. Walking shoes may also have a higher offset with more cushioning in the heel because the heel strikes first when walking.
Running shoes have more flexibility in the sole and a different cushion distribution to account for the stress of running. Runners typically have a mid-foot strike versus a heel strike, so the design of the shoe offers reinforced support and cushioning throughout the footbed rather than extra in the heel. However, some people heel strike when they run too, so there are running shoes with hefty heel cushioning as well.