Lock View Focus vs. Lock View Position

If I have an assembly that has just enough mates to leave moving parts flexible but I want a drawing view to remain in a certain position, regardless of whether I move parts around within the assembly itself, would I choose 'Lock View Focus' or 'Lock View Position'. I'm a little unclear on exactly what the difference is between the two.

After answering the question, if you could explain the difference between the two, that would great as well.

Thanx

SolidworksDrawings And Detailing