The major differences between COUs and CO Groups are

• Any CO Person can create a CO Group; only CO Administrators can create COUs.
• CO Group Memberships attach at the CO Person level, whereas COU memberships attach at the CO Person Role level.
• Management of CO Group Memberships is simple (e.g., manual management by the CO Group Owner, self-opt in for open CO Groups, etc.), whereas COU memberships can be managed using Enrollment Flows and Expiration Policies.
• COU memberships imply CO Group Memberships (in the Members:COU group).
• Email Addresses can be attached to CO Groups via CO Email Lists.