Groups are used to organize your iOS devices. They enable devices within the group to be configured with the same applications and profiles.
In this example we have the top level for the District, then sub groups representing each school
So Profiles and App Packages placed into District will automatically be deployed to devices in any of the Schools
Sub groups allow organize additional devices that will automatically inherit the applications and Profiles from the header group.
In this example we have a sub group in the High School called Library
Devices in the High School - Library will inherit Profiles and App Packages from High School and District.