Members in your workspace have access to all of the content in your library, at varying levels of permission: admin, editor, and viewer.
Guests are members of your workspace too, but they only have access to the boards on which you invite them. Air also offers various levels of permission for your guests: editor, commenter, and viewer.
Using the range of permission options across members, guests, and shared public boards, you can give any teammate, partner, or collaborator the access they need!
To learn more about members and guests, check out this article on Air's user types.