When inviting members into your room to participate you will notice that you have the ability to assign several different roles. Select the "People" icon from the left navigation in your room you will be able to view and manage everyone within your room as well as be able to view their roles.
Explorer: Can only view assigned Missions and their own contributions to those Missions. This "Mission-only" user role is great for conducting blinded research with consumers or keeping an internal team focused on their Mission since they won't see your room or its walls.
Participant: Can view all room details and content, and add/edit their own contributions.
Moderator: Can view and edit all room contributions, missions, people, and room settings.
Remember, these roles are assigned at the Room level, not community. You can invite people into your room that may not be a member of the community allowing them to only view content that is in the room, they will not see any other project outside.
*Guests: The "guest" flag is at the community level, guests are tagged in the people page of the room so you know that they don't have access to other room and in order for others to know that guests are participating in that room so they may choose to not post specific content in that room.