LISTENER.ORA is the server-side configuration file that contains network parameters for the Oracle Net Listener, including the listener address, port, service names, and protocol settings. INIT.ORA contains database initialization parameters, SQLNET.ORA is for client-side SQL*Net configuration, and TNSNAMES.ORA is a client-side file for database service name resolution. The listener.ora file is specifically responsible for defining how the listener accepts network connections.