The Render Panel shows your model based on the selected view mode.
Preview (F5,F9) – A roughly rendered view of the model
Surfaces – Shows only Faces of a rendereds model ( same as Preview- F5, can togle with F10,F11 without re-render)
WireFrame – Shows only edges of a rendered model
Thown Together (F12) – A view showing all the objects wether they are subtractive or additive.