Does any one know what the difference between these two options in the plot settings is?
the solidworks help file says: Inlet and Outlet. Presents how the flow moves inside the part as viewed from the inlet or outlet perspective.
this seems a little ambiguous to me, are they saying it is colouring the pipes with relation to the inlet velocity or outlet velocity?
It works like this: take the inlet surface for example and divide its area by the number of trajectories, take the center of each "sub" area and then trace that point across the domain till you reach the outlet. The same applies for the other direction. You do not get the same view of the flow field. In the ball valve example you have uniform inlet flow (more or less) and a jet crossing the outlet biased to one side due to the constriction. This produces a big recirculation zone of flow coming in the "outlet". see images below.
I put the other image together just to highlight the complexity of the flow in something as simple as the ball valve example. It shows the horseshoe vortex due to upstream constriction particularly well.