What’s the Difference Between Lean, Six Sigma and Lean Six Sigma?

what is the difference between lean, six sigma and lean six sigma

If you’re new to Six Sigma and interested in getting a quality improvement certification things can get confusing quickly. One question that often causes confusion is, what’s the difference between Lean and Six Sigma?

To better make sense of this question we first must understand that there are 3 main methodologies, which include: Six Sigma, Lean and Lean Six Sigma.

Below we will go into detail on each methodology and explain how they differ from one another.

The Difference Between Lean and Six Sigma


What is Lean?

Lean is very different from Six Sigma.

Lean is concerned with efficiency. It focuses on how operational processes are designed and managed to minimize inefficiencies that can be attributed to the following.

  • Delays
  • Errors
  • Waste

lean vs six sigmaConsider the challenges faced by the crew, staff and vendors of Royal Caribbean Cruise lines when the Symphony of the Seas docks early AM on Saturday mornings at the Port of Miami. Between 9AM and 4PM nearly 7,000 passengers depart the ship and another 7,000 board. While this is a challenge by itself, consider what goes on behind the scenes. More than 20,000 pieces of luggage must be moved, 2,759 staterooms cleaned, trash unloaded, and food supplies replenished. This carefully orchestrated process leaves no room for delays, errors or waste. Every step must be efficient. Or, to say this another way, the turnaround process must be Lean.

There are so many other situations where process efficiency is key to delivering customer value. Emergency departments at hospitals must be designed to minimize delays so patients can be seen soon after they arrive. On-line retailers must design logistics processes to minimize order processing delays and, in many cases, to deliver in one day, and manufacturing operations must be designed to minimize the waste associated with unnecessary process steps.


What is Six Sigma?

Six Sigma, on the other hand, focuses on:

  • Quality
  • Consistency

By consistency we mean delivering products and services that day-after-day meet quality standards; the product we deliver today is just like the one that is delivered tomorrow.

When we eat a restaurant, purchase a new hard drive, or travel on an airplane, we expect a certain level of quality. The role of Six Sigma is to ensure that this level of quality is delivered to the customer.

Sometimes, companies fail to meet this challenge.

lean six sigma takataTakata a Japanese manufacturer of auto airbags is one such example. These airbags relied on a compound of ammonium nitrate that expands upon impact, inflates the bag, and thereby protects the driver and passenger from head or body injuries.

However, the compound broke down when exposed to moisture and temperature swings. Some accidentally exploded sending metal fragments though the passenger compartment. In total 19 auto manufacturers recalled approximately 37 million vehicles in which over 50 million airbags were replaced. It was the largest recall in automotive history. Moreover, the human toll was substantial. Twelve people died and almost 200 were injured.


difference between six sigma and lean six sigma boeingThen there were the Boeing Max 8 disasters when two aircraft, within six months of each other, crashed shortly after takeoff. In total, 346 people died. The problem was traced to software problems in the Maneuvering Characteristics Augmentation System (MCAS). As part of the auto pilot system, the MCAS prevented the pilots from overriding the system and recovering from the steep descent. They tried to overcome the system controls but failed.

While the Takeda and Boeing failures reached headline status, there are countless stories of quality failure, less known, but nonetheless underscoring the challenge that organizations face to assure their products and services meet quality standards.

The job of Six Sigma is to prevent these failures by instituting effective quality control processes at the manufacturing or service level before it’s too late.

This, then, is the difference between Lean and Six Sigma. Lean focuses on efficiency while Six Sigma focuses on quality. Both are essential to support sustained competitive positions in an industry.


What is Lean Six Sigma?


Lean Six Sigma serves as a hybrid approach that combines the best of Six Sigma (quality and consistency) with the best of Lean (efficiency) to help organizations deliver customer value through efficient operations and quality standards, which results in creating higher quality products and services. Because it’s approach tackles both issues, Lean Six Sigma has become the most popular methodology in industry. From healthcare to government agencies, Lean Six Sigma is can be applied to almost any industry and any job function.

The benefits of Lean Six Sigma are widespread. These benefits help organizations to:

  • Increase Profits
  • Decrease Costs
  • Improve Efficiency & Quality
  • Improve Customer Satisfaction
  • Enhance Employee Development


Lean Six Sigma Certification Belts


Certification in Lean Six Sigma as well as Six Sigma is broken down (beginner to advanced) into different belts. These belts include:

Learn more about which Six Sigma Belt is right for you.

Because Lean Six Sigma is a hybrid of both Lean and Six Sigma, the material covered in a Lean Six Sigma certification program generally covers everything that is also covered in a standard Six Sigma program. The only difference is that there is additional coverage of Lean in the material.

All three methodologies are designed to help organizations become more competitive in the marketplace. Those with knowledge in Lean, Six Sigma and Lean Six Sigma are in a position to add sustainable value and take a lead role on implementing process improvement initiatives. If you are interested in becoming certified, check out Six Sigma Global Institute for more information on Lean Six Sigma certification and training.