The engineer in me would assume that they do some basic calculations (damping/valving, spring rates in combination met weight, suspension geometry, ...) etc.
Most coilovers are pretty generic I'd say (the main differences in construction being one or two way adjustable), the difference would be in the setup (valving, spring rates, ...) and the quality of the build.
Recent improvements include use of magnetism, electronics, sensors and smart steering (even including gps or camera technology), next to further advances in geometry. Maybe some steps have been taken in valving refinement.
All just my humble opinion of course (not involved in car stuff in a professional way!).