What's the difference between business units in Oracle E-Business Suite and Oracle Fusion Applications?

In Oracle E-Business Suite, operating units are used to determine in which ledger a given subledger transaction is accounted and to partition set up reference data, processing and security.

In Oracle Fusion Applications, enable business units with all their business functions to replace your operating units in the Oracle E-Business Suite. Oracle Fusion Applications provide the additional functionality of assigning a manager to the business unit.