If data sets can be shown to be dissimilar, that is an indication that the factor which separates the two data sets has a significant impact on process or product performance.
Finally, the goal is an improved process, product or service that better meets the customer expectations.
These three elements reinforce each other.
As you can see, the individual is usually expected to lead several projects simultaneously while acting as coach for a handful of Green Belts who are leading their own projects.
These individuals lead large cross-functional projects and serve as coaches for the Green Belts in that department or location.
As you can probably tell from both of these lists, the principles of Lean can be applied to any business process or operation, not just manufacturing.