As the name implies, a new thing called the Asset Bag. When right clicking a block in the Hierarchy, a new option appears to send a copy of it and all its children to the assets bag. In the animations tab, clicking edit on an animation will have the same option. When adding an animation, any animations applied to parts that aren't roots will be applied to parts with the same name as the original. (Sorry for bad explanation, I am tired and woozy)