Database User 
Database users can use SQL statements to process data in the database instance. They can do this, for example, by using the database tools SQL Studio, Web SQL Studio, SQLCLI, and the Loader.
Database users cannot log on to the Database Manager. You can, however, use the Database Manager GUI to create and manage database users.
See also:
Concepts of the Database System
Conventions for User Names and Passwords
Database Manager
GUI, 
Managing Database
Users
SQL Reference Manual, Authorization