The managed and managed-plus users are offerings for MSSP end customers and as such are a hybrid between a collaborator and a full user.

The managed user is useful for an MSSP who wants to run a hybrid SOC together with their end customers.

 The managed user will have full case management capabilities on their own environment (similar to the MSSP analyst)

The managed-plus user is the same as a managed user but with the ability to build and edit playbooks in their own environment.
They will be able to view playbooks running in their environment such as "All environments" playbooks - but will not be able to edit playbooks if they don't have permissions to all the environments that the Playbook is associated with. 

So for example, a user with permissions to the environment "North England" only - will be able to view but not edit a playbook that is running on "North England", "South England" and "East England." environments. Moreover, this user will not see that this Playbook is running on "South England" and "East England" environments.

The MSSP is responsible for managing the Marketplace, configuring the integrations and agents and customizing actions in the IDE for the Managed-plus user. 

For more information, refer to Create a Managed/Managed-Plus User.