User Property Vs. Parameter

Greetings,

When I create a user property (using 'Properties > Define other properties ... '), a related parameter is created.

eg. If I create a user property 'Author', a parameter name 'Properties\Author' is automatically created.

Is there any specific capability / use that User Property can perform that a parameter related to the user property or a User Parameter does not have?

Thanks in advance for your responses.