Lead lists, calling numbers, CRM and communication integrations, call history, and reports belong to the workspace, not to a specific user.
The default calling strategy and lead custom fields are also configured at workspace level.
Interface preferences, language, whether the sidebar is collapsed, avatar, and sign-in email are linked to your user account.
Callback tasks are assigned to a specific user. Tasks you create are assigned to you by default.

Admin: can invite users, configure integrations, set the calling strategy, and manage billing. Member: can make calls, manage their tasks, and view reports.
A user works in one workspace at a time.
Calling numbers are purchased for the workspace and then assigned to members by an admin. An unassigned number cannot be used to make calls.