What's the difference between an Oracle database user and a portal user?

Related topics

Oracle database user accounts (schemas) can be created:

Any privileges granted to the schema are valid only in the database itself, not in the Database Navigator.

Oracle Portal user accounts can be created:

Any privileges on database objects granted to a portal user are valid only within Oracle9iAS Portal.  

Related topics

Managing users and groups
What are the different types of user accounts?
What is a portal administrator?
What is a public user?
What is an authorized user?
What users are created by default?