Does it have to be one or the other? 

In this case, photographing the stream in the shadows of the setting sun had to be done first, isolated from the trees and distant rocks which were IN the bright golden hues of the setting sun.  

The water is presented as smooth because of a slow shutter speed which accommodated the shadows;  the trees are sharp, because of a fast shutter speed and a bright sun.  Hence two separate photographs were taken.
Once each was completed and developed separately, they were combined.  This is what the eye would do--look at the water then the brightly lit trees, and in between switching back and forth, the eye would get larger or smaller, adjusting to the shadows or the sun. 

This could not be done photographically, as one exposure. 

So I do the same thing the eye does: first I photograph or look at the water, then I make camera adjustments and photograph or look at the bright trees and rocks.  Two exposures are made with two radically different factors taken into account:  the shadowy water, and the bright shaking tree leaves.  And what beauty we see, when both are combined.  Something the eye could not do.

Do you like it?  Do you have questions?  I'd love to hear from you.
John