They have access to all spaces and information. They can also invite other users and update their roles.
They are members/owners of your spaces. They can't invite users to a portfolio, however, they can see some reports about their space tickets, activities, and users in the portfolio and the defined access to each space you invited them to in the portfolio.
They will see a start page listing the spaces and activities that they are working on with you and the defined access to each space you invited them to in the portfolio.