I recently got a valid question from a collegue and it deserves an answer.
"When do I use Scrum and when do I use Lean?"
Lean predicts that work happens in a certain order. Scrum has a "chaos" approach where work can be done in best possible way, dictated by the situation.
Therefore Scrum works better than Lean in environments with rapid change, on the edge of chaos where the same solution rarely work twice.