Q: How is this different from a normal progressive lowering spring?

It is a third category, closer to a motorsport stacked-spring setup than to a progressive spring. A stacked setup uses two linear rates with a defined transition point between them, which gives predictable results while allowing real tuning of handling. This spring copies that idea inside a single coil: two engineered linear rates with a specific transition point, so response stays consistent and easy to learn rather than constantly changing as a progressive spring does.