What other process improvement method can be used instead of Six Sigma, how do they differ?

Apart from six sigma, there are many other techniques that companies use to improve their processes and positively impact their quality. Total Quality Management (TQM), Business Process Reengineering, CEDAC, Drive, Benchmarking and Statistical Process Control are some of these processes. The one that intrigues me is Total Quality Management or TQM. The primary difference between TQM and six sigma is that TQM focuses on improving the specifications and characteristics of the product or service to fully satisfy the customers while six sigma focuses more on reducing defects from products and services.