Lean vs Six Sigma?

I am frequently asked about the difference between "lean" and "six sigma" - are they the same or are they mutually exclusive? My view is that they are different tools that adress different issues. Lean is primarily about reducing waste. Six sigma is primarily about reducing variation. Both lean and six sigma are work processes that have a variety of specific tools, and many tools are common to both work processes. As always, I say focus on the problem you are trying to solve and use whatever tool, tools, or work processes are appropriate to find the solution.