Someone last week asked me, what's the difference between Best Practice, and Lessons Learned.
Now I know that some KM pundits don't like the term "Best Practice" as it can often be used defensively, but I think that there is nothing wrong with the term itself, and if used well, Best Practice can be a very useful concept within a company. So let's dodge the issue of whether Best Practice is a useful concept, and instead discuss it's relationship to lessons learned.
My reply to the questioner was that Best Practice is the amalgamation of many lessons learned.
If we believe that learning must lead to action, that lessons are the identified improvements in practice, and that the actions associated with lessons are generally practice improvements, then it makes sense that as more and more lessons are accumulated, so practices become better and better. A practice that represents the accumulation of all lessons is the best practice available at the time.
See the diagram (though really instead of a steadily increasing arrow, it should go up in small incremental steps, but that's beyond my drawing ability).