TileDragDropService is a derivative of RadDragDropService. Hence, it handles the whole drag and drop operation in RadPanorama.
By default, when the RadPanorama.AllowDragDrop property is set to true, the user is allowed to reorder the tiles between the groups or within the same group. When you start dragging a tile and you hover another tile it is shifted to the right. It is achieved by an AnimatedPropertySetting for the CellPaddingProperty.
The AutoScrollOffset property of the service gets or sets the offset from the edges of the control at which automatic scrolling starts. The service doesn't offer a specific public API that is different compared to the one offered by RadDragDropService. If you want to customize the default drag and drop behavior, you can refer to the Tiles Drag and Drop help article which demonstrates a sample approach how to accomplish tiles drag and drop functionality between two RadPanorama controls.