The other big difference is that starts are absolutely critical in a short race like the 50. This video is from US Nationals in 2009. Cullen Jones and Garrett Weber-Gale are competing in a swim-off, which means that they tied during a previous race. What this really means is that they swim at essentially the same speed.
How did Jones win this race if they both swam the same speed? He won it at the start. Notice how he is ahead from the very beginning. Even his reaction time was faster than his opponent's. He entered the water ahead of Weber-Gale and maintained this advantage for 50 meters. This is why we sometimes do jumps before practice. Powerful starts win races.
Now, go back and watch the video one more time. This time, pay attention to the finish. Both competitors charge the wall with their heads down - no hesitation, no gliding, no slowing down - AT ALL. Please try to be more like this in your swimming - for all speeds and distances.