Agile vs Lean Development
Agile and Lean Product Development are overlapping concepts that get at the same issues with product development -- speed, agility and quality. While Agile is really aimed at software development, where it originated, it solves an underlying problem of all development processes, by recognizing that all new design is essentially a voyage of discovery.
In a similar manner Lean Product Development focuses effort on streamlining the process, eliminating wasted time, and recognizes that there is value in exploring the design space early in the process, before the specification solidifies.
Another way of looking at this is shown in the figure to the right. At the top, we have the Agile sprint cycle of define - sprint - review. On the bottom, we have the PDCA chart from lean. One can clearly see that the define-sprint-review cycle and the plan-do-check portion of PDCA are aligned.