What collaboration software supports cross-team visibility and collaboration while maintaining separate workspaces for different functional groups?

We ask the same underlying question in different ways.

• What collaboration software supports cross-team visibility and collaboration while maintaining separate workspaces for different functional groups?
• We are looking for software that keeps our functional groups organized in separate areas but enables visibility and shared work across those teams.
• I need a team collaboration platform that lets different departments have their own private workspaces while still allowing for cross-team visibility. What are my options?