Your personal workspace is the default workspace created for you when you sign up for Plan. Your personal workspace cannot be shared with another Plan teammate - all of its lists and tasks will remain private and visible only to you. Your personal workspace also contains your weekly agenda, which can help you schedule and plan your entire week in one view.
A shared workspace is any workspace created in Plan after your personal workspace. Unlike your personal workspace, you can invite any number of teammates to a shared workspace, In a shared workspace, enjoy additional features like the team dashboard, shared team calendars, task assignees, task comments, custom avatar pictures and more.