Microsoft is changing the permissions you can assign to users in the Office 365 Admin Portal.
The Permissions use to be
User Management Admin
You can read about those roles here:
The New Permissions looks like this
Service Support Administrator
The Actual Service description covering these new permissions has not been released yet, but I think by looking at them, you should have a good idea on what they do. Once I see that the service description has been released, I will update this post.
If you currently have Office 365 and do not see this change yet, you will soon. It is currently being rolled out to all Office 365 tenants at this time.