This article by Steve Towers give a good insight to some differencies between Lean, Six Sigma and CEMM (Customer Expectation Management Method)
He points out this phrase:
“you may be doing things right, but are you doing the right thing?”
and it’s important to think about this when working with process improvements.
As an example you could provide the best product on the market (doing things right) but if no one is interested in that product, then you should concider if you doing the right thing.
You find the article here