From the Cisco network security material:
The group-object command is used to construct hierarchical, or nested, object groups. The group-object command, which is not to be confused with the object-group command, places one object group into another.
The difference in object groups and group objects is as follows:
- An object group is group consisting of objects.
- A group object is an object in a nested group and is itself a group.
If they hadn't written those paragraphs, I would actually be less confused. 8^P