Scene Graph & Grouping
All 3D objects within the project are stored in a hierarchic tree structure called a Scene Graph. That means that each object inherits the position, rotation, and scale values from its parent object. All child objects will be always relative to their parent. Dynamic objects like Motors also can therefore manipulate their child's relative positions.
A position or rotation in object space means that it might be relative to their parents
This is the absolute position or rotation in world coordinates.
The hierarchy position of an object can be changed by dragging an object within the 3D Hierarchy window.
By default, the object's World-Space position won’t be changed, because it will calculate a new relative position depending on the new parent Object.