These two files were shot within a fraction of a second between exposures. The only difference, in camera, was the exposure. The shot above is two stops higher than the metered average exposure and the shot below is two stops lower than the average, according to the camera meter. Two stops can make the difference between a good photo and one that needs a lot of work to be saved. But the camera meter doesn’t know this so it tries to make the best average exposure it can to save the photo and a high percentage of the time, it’s usually right. Some photographers are good at second guessing the meter and choose to shoot manually. I’ve set my meter to a constant minus (-) 1/2 stop difference because I always thought the Nikon meters tend to overexpose a tiny bit. RAW files are so forgiving of this amount of exposure it’s almost negligible though. I think the biggest difference is within the scene itself and the way we want to portray it.
PS: Here is the top photo with the ducks swimming in the opposite direction. I found these same three ducks and re-staged this sunset to get this photo.