Also, UX Packs has slightly smaller installer size than Transformation Packs.
UX pack gives you less risk of damaging system. So if you want to fully integrate the theme pack, go for Transformation Pack. As both is for nearly same purpose, when you are going to download and install any of these theme packs on your Windows, it may come to your mind that which should I get? Transformations or UX pack? Actually Transformation Packs is a complete solution which will modify your system files (of course you can revert back) to give you more native experience, where UX pack, as it sounds, will not modify system files, rather give you mentioned User Experience in limited form. One kind is Transformations Pack and another is UX Pack. WindowsX team typically develops two kinds of theme packs. Transformations or UX Pack? Which should you Install? You can just consider these packs as powerful Mac OS X Yosemite Themes for Windows.
Your Windows OS will continue to work as the way it worked before. Thus you will feel very near user experience that on Apple’s OS. From your Windows side, it will resemble Apple’s iOS 8 and OS X Yosemite graphics.