The ClickUp Hierarchy is the base of the entire platform. The Hierarchy provides an organized way to break work down into actionable items for your whole team to collaborate.
Workspace - everything happens here (the overarching "business" unit that holds everything else) - only have one per business.
Spaces - high level categorizations (teams, departments, etc.).
Lists - group together related tasks (lists can also be further organized into folders).
Tasks and subtasks - where the work actually get's done and all of the task details, checklists, etc, are housed.