This video describe the Model Tree View in the model tab. Tree View allows managing the objects in the model. It depicts a road map of the model and how it evolved. This also describe cumulative single solid principle.
Parts and Bodies are manipulated to create the final model. Each body can be activated and deactivated.
Standard part is used as container.
Also, it is important to understand the differences in part and part design workbenches and how they could be used to produce complex models. While part and part design workbenches can be used independently , there are occasions where they can be used jointly as well.
See following videos
Modeling only using Part workbench :
https://youtu.be/c8_b8tedeNA
Modeling only using Part Design workbench :
https://youtu.be/DxzXt5vLiiA