Formal/Hierarchical:
* Hierarchy
* Command structure
* Reporting structure
* Organizational chart
* Line of authority
* Ladder of command
More general/Informal:
* Line of responsibility
* Reporting system
* Management structure
* System of authority
* Decision-making process
The best synonym will depend on the specific situation and what you're trying to emphasize. For example, "hierarchy" might be a better choice if you're discussing the formal structure of an organization, while "system of authority" might be better if you're discussing the way decisions are made.