The validator-rules.xml file is provided by
Struts and contains the definitions for the "out of the box" validation rules.
The validation.xml file is unique to your application, which means that you have to create it. It contains <form> and <field> elements defining the specific validations for your application. For examples, see the struts-examples-1.3.x.war and struts-blank-1.3.x.war files that come with the download.