User groups are a group of users, eg. departments / business. You can change and create new user groups as well as move a user from one user group to another.
When operational organization units are used, the "Operational organization unit" field can route cases from user web to the proper operational organization unit.
More Service Discovery automatically retrieves information about which OUs the users are associated with and automatically creates it as user groups in More Service. You can manage and make access to this.
It is possible to tag a user group as "External".