Christmas and Pet Buddy sections are AR apps. According to Apple, ARKit runs on iOS devices with the A9 and A10 processors.
Based on Apple's guidelines, here are the iOS devices that will be able to run ARKit apps:
iPhone 6s and 6s Plus
iPhone 7 and 7 Plus
iPhone 8 and 8 Plus
iPhone X, XS and XR
iPad Pro (the 10.5-inch model, 12.9-inch model, and the older 9.7-inch model)