In version 1.8.0, we added two new features: Group, and Command Event.
Group
Group is an editor feature to help us visualizing and organizing the nodes. Any nodes inside the box will be moved along when the group is dragged.
You can read more about this feature in Group page.
Command Event
The built-in UnityEvent can't be used in a command, because it doesn't support cross-scene object references, which is the reason why CommandEvent is created.
A new command type, Invoke Event, is added. It is a command that simply invoke a Command Event upon execution. We can also use CommandEvent in a custom command script, in case we have our certain rule on which condition that Command Event should be invoked. You can read more about CommandEvent here.