To begin with, the two rock gardens in question are very different entities. That in the prior photo is a hillside rock garden, wild and tempestuous. The setting for the rock garden above is much tamer: it is a display area at a garden center.
But beyond this fundamental distinction, note how differently texture is used -- and to what effect. In the photo above, plant selection was made with an eye to continuity in texture. It's almost two-dimensional, a perception aided by the short heights of the plants.
