What is SADM?
Is it Scrum? Yes. Is it XP? Yes. Is it Lean? Sure, why not. It is a combination of all of them. One day I read The Marriage of Lean, Scrum and Extreme Programming (XP): How to Align Agile Across an Organization and thought this article explained pretty much what we were doing when we implemented the Scaled Agile Framework. We first taught everyone about Scrum, then we quickly moved to teaching teams about XP. While teams were learning about XP, we taught our leaderhip group about Lean practices.
So SADM is all three of them; Lean, Scrum and XP.