Administrator: creates the team, has access to the billing section, can see all data, can assign deals, contacts, notes, todos and events. You can have multiple administrators in your team.
Manager: has some powers only on users in his circle and circles underneath. He can create areas and invite other users in the team.
Collaborator: can work on his data and collaborate with other users who are in the same circle or circles underneath.
How to change roles
Only the administrator can change the role of users in his team.
To change the role, select the user you want to edit. On the right of the window you can see his profile: from here click on the drop-down menu to change his role.