What is the difference between an administrative lock, a user lock, and an element-level lock?

• An administrative lock is performed by an administrator using the Revit Server Administrator tool or Revit Server Lock Command-Line Utility to lock the server.
• A user lock refers to data or permission locks that are applied to a model by a team member in the Revit application to manage concurrent access to a central model. This type of lock may remain locked if a team member’s system closes unexpectedly or the network becomes unresponsive during a server-based transaction. In this scenario, the administrator needs to clear the lock.
• An element-level lock prevents multiple team members from changing the same element in a model at the same time. See Editing Workshared Projects.
  Note: User and element-level locks are applied transparently by Revit, not by the user directly (unlike the administrative lock, which is explicitly applied.