In 1981, Motorola (not General Electric) developed a business management strategy called Six Sigma to improve the quality of process outputs. Six Sigma uses statistical methods to help identify and remove causes of defects.
Although six sigma is used across various industries, it’s been primarily adopted by Manufacturing and Financial Services. Companies that sponsor six sigma, train and certify individuals to be experts in these methods. These experts are called Green Belts, Yellow Belts, Black Belts, and Master Black Belts (listed in order of expertise progression).
In 1984, the Project Management Institute (PMI), a non-profit organization, launched the Project Management Professional (PMP) Certification. The PMP contains 42 processes that can be adopted to improve the success rate of projects.
In recent years, many governments, companies, and organizations have taken an interest in acquiring individuals who are PMP certified.
These are the 5 lifecycles within PMP and Six Sigma.
Although the lifecycles are similar, the main difference lies in the methodology. PMP uses various processes to help improve the project success rate whereas Six Sigma leverages statistics to eliminate defects or waste.
Of course today everything has evolved including project management methodologies. There are a lot more styles including: Agile, Hybrid and Waterfall to name just a few.