What is difference between uno and dual in oracle?

@dalton_moen 

In Oracle, UNO (User-Named Objects) and Dual are both special system tables, but they serve different purposes.

• UNO (User-Named Objects): UNO is a self-defining conceptual schema that represents an integrated design view of all objects a system needs to be aware of in order to function. It includes built-in objects as well as user-defined objects. UNO is a broader concept that encapsulates all necessary objects in a system.
• Dual: Dual is a dummy table used in Oracle to perform calculations without selecting data from any actual table. It is a special one-row, one-column table created by Oracle that is used in SQL queries primarily for purposes such as selecting a constant value, performing arithmetic calculations, generating sequence values, or simulating the presence of a table when there isn't one required for a query.

In summary, UNO encompasses all objects in a system, while Dual is specifically a dummy table used for various functions in SQL queries.