Marc challenged us today:
Oh, and does anyone have a succinct definition of the difference between lean and agile?
I’ve been thinking about this too, and had an epiphany.
Agile focuses on early delivery; it handles changing values.
Lean focuses on cheap delivery; it minimises waste.
Since unsuccessful delivery would be waste, Lean happens to focus on successful delivery; and since delivery of poor value requirements would be waste, Agile has some focus on cheap delivery. But Lean’s focus is all about trimming the fat everywhere, whatever other practices and processes may be used, and I think it therefore represents better value-for-money.
I accept that Agile has taken some practices from Lean, and that its focus may have shifted somewhat, but I’m pressed to think of a practice that Lean’s taken from Agile. I also accept that I’m biased towards the meaning of the names of each of the different practices, and the focus which those names have impressed upon me. Since names suggest behaviour (consider horses called Thunder and Buttercup), I expect that others might be similarly biased, whether they know it or not.
Liz Keogh, lunivore 
You’re looking for a distinction that isn’t really there.
Lean also focuses on early delivery. In fact, one of the seven core lean principles is “deliver early”.
Lean and Agile are just two different intellectual frameworks for understanding and expressing the same concepts. Some people can “get” lean better as it speaks more in business terms than agile does. The fact that people study Toyota’s success in every business school in the world doesn’t hurt.
Agree with your first respondent that “focus on early delivery” is probably not a good way to distinguish agile from lean.
But disagree with the assertion that there’s no distinction to elucidate. The other three parts of what your summary sound right; and your observation that processes haven’t crossed back from agile to lean also rings very true.
Another perspective: agile as a specialization of lean to particularly uncertain and unpredictable contexts.
NetObjectives did a series on this:
http://blogs.netobjectives.com/2006/07/23/lean-values-in-the-agile-manifesto/
Hi Liz,
I’m not sure that there is any real difference between agile and lean. They are just different applications of the same school of thinking, applied to different industries. As you say “names suggest behaviour”, so my sense is it this is more a question about naming than anything else.
If you haven’t read it already and are interested in some of the original thinking behind both lean and agile then I might suggest the “Toyota Production System” by Ohno.
Robin.
I accept that I’m biased towards the meaning of the names of each of the different practices. Language has an emotional impact.