Difference between Lean and Six Sigma

The difference between Lean and Six Sigma can be summarized as follows:

Six Sigma = Reduced process variation
Lean = Improved process flow

Let's take a look at each.

What is "Lean :
The practice of "Lean" involves breaking down processes to the "bare bone essentials", hence the name "lean". The Lean approach to waste is that "Non-value added is waste". Hence, in practicing Lean, the goal is to segregate waste from value in processes, and eliminate the waste and non-value added.

The typical method for practicing Lean is to do the following:
1. Identify Value
2. Define Value Stream
3. Determine Flow
4. Define Pull
5. Improve Process

The focus of Lean is on Process flow. Tools used for the practice of Lean are oriented to visualization, and include tools like Microsoft Visio.

What is Six Sigma:
In the Six Sigma approach, the view on waste is that "Variation is waste".

In practicing Six Sigma, the DMAIC method is used:
1. Define
2. Measure
3. Analyze
4. Improve
5. Control

Six Sigma is a "Problem focused" methodology, and the primary toolset of Six Sigma is Math and Statistics.