The Difference between Typical Project Management and Six Sigma Project Management.

The Project Management Body of Knowledge (PMBOK) became an accepted standard (as established by the Project Management Institute) that is still widely used in many industries around the world. At a basic level, many of the methodologies advocated by PMBOK and Six Sigma have a great deal in common. Both seek to establish a sound plan; identify and communicate with stakeholders; conduct regular reviews; and manage schedule, cost, and resources.
Six Sigma is not just another project management initiative or process improvement programme. Six Sigma is not just a new term for project management nor is it a mere repackaging of old concepts. It is more than that because it is a robust continuous improvement strategy and process that includes cultural and statistical methodologies. Six Sigma is complementary with existing project management programmes and standards but differs in significant ways. Both disciplines seek to reduce failures, prevent defects; control costs and schedules, and manage risk. Generally, professional project management attempts to achieve these goals by encouraging best practices on a project-by-project basis, often through the mechanism of a project office that promulgates policy, provides templates and advice, promotes appropriate use of tools such as critical path method, and perhaps performs periodic project reviews.
Too many project management methods have failed not because they weren't adding value but because you couldn't measure the effectiveness of the methodology or quantify the value added by process changes. Six Sigma provides a structured data-driven methodology with tools and techniques that companies can use to measure their performance both before and after Six Sigma projects. Using Six Sigma, management can measure the baseline performance of their processes and determine the root causes of variations so they can improve their processes to meet and exceed the desired performance levels.