This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
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.