The function that distinguishes commercial banks from the central bank is that the former

Commercial banks are financial institutions that accept deposits from the public and use those funds to provide loans and other financial services to individuals and businesses. On the other hand, the central bank is a government-owned institution that oversees the banking system and manages the country's money supply. The central bank is also responsible for implementing monetary policy, regulating the foreign exchange market, and serving as a lender of last resort for commercial banks in times of financial crisis. So, the main difference between commercial banks and the central bank is that commercial banks accept deposits from the public and provide loans, while the central bank manages the country's money supply and regulates the banking system.