Six Sigma work, by general definition is approximately or less than "3.4 defects per 1 million opportunties for defect" Source: Wikipedia.org (yes I took the easy road instead of a more vetted source). Six sigma is also primarily a process to identify the most frequently occuring or big problems and work to solve those first, with specialized and skilled teams, then each additional item with the most amount of occurences or problems is then tackled. Ultimately striving for 0 customer seen defects.
The lean manufacturing is, quoting again from Wikipedia out of convenience, "is the optimal way of producing goods through the removal of waste and implementing flow, as opposed to batch and queue. " I did kinda sorta have an ah ha moment this morning when reading a quote from Barbara Wheat and Chuck Mills book Leaning into six sigma "If you go and make everything a Six Sigma problem, you're going to constipate your system and waste a lot of resources." MMM, food for thought.