Dripper

Dripper is a simple app powered by Automator. It extracts differential files from the folder that you dropped and the tree structure of folders and files is kept.

When you dropped a folder, Dripper ask you the search conditions. If you determined it, Dripper operates according to them. And it extracts differential files to your desktop.

You can download Dripper from my blog. (Sorry, texts are Japanese.)
http://blog.worldending.jp/mac/dripper.php

* Please avoid dropping the folder that contains quite a lot of files. In that case Dripper cannot guarantee normal operation.