What is actually a "Graphic Group"?

Hi.

I see 2 ways to create a Group in MicroStation:

- Group

- Named Group.

Group is very limitated because I understand we cannot add/remove elements later. And it is basically a Cell.

I understand that "Graphic Group" is a Named Group...

Because tools such as "Add to Graphic Group" and "Remove From Graphic group" are only for "Named Groups".

http://www.mdlapps.com/microstation/ustnhelp286.html#F26021

There is also "Graphic Group Lock" (ON /OFF) for Named Groups.

Why Bentley differenciates between Graphic Group and Named Group? is not the same? Is the old name of Named Group?

Thanks.