ARKit 3 adds 1) automatic real-time occlusion of people and 2) real-time motion capture

RealityKit is part of ARKit. Lets developer blend and auto-scale virtual objects with the real world environment. Photorealistic rendering, animations, physics, audio effects.

Reality Composer lets developers create interactive scenes with AR support. Virtual objects library. Can animate and trigger virtual objects in scenes. Runs in XCode and as an iOS app.