1. Traditional Six Sigma (TSS): It effectively integrates the Six Sigma business process reengineering and project management bodies of knowledge and has also been effectively tailored to financial services, healthcare and other specialized industries. As a result, it is no longer limited to typical brick and mortar manufacturing companies.
2. Lean Six Sigma plus (LSS+): Under the LSS+ model, Champions and Master Black Belts make a determination as to the type of problem under consideration and then determine the method best suited to the problem in terms of time, cost, quality and the predicted results. If a Six Sigma approach is warranted, a project is launched under the traditional define, measure, analyze, improve and control (DMAIC) model. After the analyze phase is completed, however, the Champion and Black Belt could decide that lean tools might provide a more effective solution. On the other hand, if a lean approach is warranted, then the duration of the define, measure and analyze phase of the DMAIC process can be shortened. If the lean tools will provide an appropriate solution, the time involved in the improve phase can also be shortened.
3. Lean Six Sigma light (LSSL): This model entails use of the DMAIC structure, a limited set of Six Sigma tools (leaning toward the simpller ones) and the mainstream lean tools. This method can be effective on well-understood problems that have to do with the flow of product or work units through a multistep process. But the number and types of problems that can be solved with the LSSL method are limited to issues pertaining to flow of work or material and to solutions that can be brainstormed without detailed quantitative analysis.
4. Traditional lean (TL): The traditional lean model involves the use of a number of tools that have been adapted from the Toyota Production System approach. The TL model has proven quite effective when applied systematically to repetitive processes involving flow of material, transactions or physical product. The TL model usually involves some basic statistical methods, such as control charting, but the main Six Sigma tools, involving data analysis and quantifying root cause are uncommon. This method has proven most effective for operations that involve the production processing or distribution of work or product.
Source: Mader, D. P. "What comes after the low-hanging fruit? Making smart choices about lean Six Sigma applications." Quality Progress, August 2008: pp. 58-60.