What are the fundamental differences between Lean Six-Sigma and other process improvement /quality improvement programs ( TQM, TQI, ISO, EFQM etc) ?  
Lean Six Sigma overlaps with many other quality programs in many areas however there are two keys areas in which it stands unique and alone.

1.  Single Piece Flow (SPF):  
 The restructuring of business processes to get away from the "Batch-and-Queue" system and differences in rates of production of connected activities which results in "queues"  of work-in-process (WIP) and "buffer inventory".

With SPF work activities change their throughput rate depending on the demand rate for the product or service by the customers.   This one rate of production by all activities to match customer demand is called the Takt Time.  Items are started and finished one at a time by Work Cells instead of once part of the product being completed by one department and then passed on downstream to a different department.

Single Piece Flow is counter-intuitive and also can be more difficult to manage (with traditional management tools)  which are two reasons why it is still not implemented in many organizations   However when the right management tools and techniques are used (  Visual Factory,  Work Cells, Takt Time, Pull, Just-in-time, Kanban, 5Ss, Poke Yoka )  then Single Piece Flow can reduce cycle times by as much as 90%, is more flexible so can respond more effectively to the voice of the customer.

2.  Measure,  Analysis and Understanding the Standard Deviation of all aspects of production:
We all know about AVERAGES for our business processes ( average production per hour,  average number of defects per shift,  average time per call ...etc ) but that is only half of the picture.   What we also need to measure and analyze is the Standard Deviation (SD) of values in all aspects of our business.    With the tracking of standard deviation together with the knowledge that  68% of all values fall within plus/minus 1 SD, 95% within plus/minus 2 SD, 99.75% within plus/minus 3 SD ...etc is a breakthrough management tool for any business to implement.