Is it true that Lean is broad while Six Sigma is more focused and narrow? Lean entails a holistic view of an enterprise process, while Six Sigma entails deployment of resources to fix a particular process. The concept takes a "leaning out" of a set of opportunities, removing waste in a system. Six sigma reduces defects. Lean minimizes waste, while Six Sigma minimizes defects (or variation).
Lean focuses on continuous improvements, while Six Sigma focuses on breakthrough improvements. Both combined focus on "the pursuit of perfection". Combining Lean and SixSigma is a powerful tool for any organization with one emphasizing agility while the other help keep quality on the fron burner. An agile process that assures optimum quality by minimizing variation provides a compelling motivation for adoption and can help guarantee acceptance and create a "quick" set of results.
Each has its own strenght, but a great amount of difference also exists.
Six Sigma and Lean both have origins in American and later Japanes process improvement laboraties, mostly in the automotive industry from Ford to Toyota. They have booth been adopted by thousands of organizations across the world to great benefits (and sometimes when improperly adopted to some loss).
Many Six Sigma and Lean experts have mostly talked up the Japanese origins of these tools and concepts; mostly out of obeisance to Toyota's impressive growth and profitability in the last two decades as it upstaged Chrysler, Ford and lately GM in nearly all of the important metrics. However, they gloss over the real innovation in management theory and business process improvements that originated in the US, nor some of the economic and political strengths and weaknesses of the last five decades that have helped to shape both the short and long term consequences that are now obvious as the American automobile industry begins to unravel, like the British auto industry had in the late twentieth century and the Asian auto industry begins to rise and dominate.
Just to make the point, nearly all important manufacturing has been moving from the west to the east for almost thirty years on, and the future simply point to more validation of that trend.
However, the concepts in Six Sigma and Lean are powerful and hold tremendous promise for any organization that commits to quality and perfection in all their outputs (internal and external alike).
One of the troubles with the Lean and Six Sigma is in their manufacturing origin and the increasing desire to adapt them to non-manufacturing industries often create conflicts for implementors. Also, the idea that Lean does not require the use of statistical analysis or that Six Sigma projects can not exceed 6 months or must be a minimum of 3 months introduce additional constrained in their deployment.
Six Sigma is heavily dependent on statistical tools and is a five stage methodology, that lays out the order of utilization of the various tools. Six Sigma stages include Define, Measure, Analyze, Improve and Control (or DMAIC), while Lean is centered around Ss (5S , 6S or 7S : Sort, Simplify, Sweep, Standardize, Sustain - SAFETY, SECURITY).