When we talk talk about Agile, we are often talking about the form of Agile. That is, the practices that are used to manage an Agile process. Most common of these are Scrum, but others include Kanban, Srumban (a combination of Scrum and Kanban) and XP.
As large organizations begin to utilize Agile through complex processes, meta-forms are used, such as Scrum of Scrum and SAFe.
The danger is, the more rigid the form, the more the essence of Agile is at risk of being lost.