Manager/Core/Watcher roles explained:
Manager — They have access to all projects and information. They can also invite other users to be managers.
Core — They are members/owners of your projects. They can see some reports about their project tickets, activities, and users in the portfolio + defined access to each project you invited them in the portfolio.
Watcher — They will see a start page listing the projects and activities that they are working on with you, plus the defined access to each of the projects you invite them in the portfolio.