It depends on the amateur and the pro. It also depends on the type of work being done.
Some shooters work very methodically and set the table for a specific shot before the lens cap even comes off the camera. They may only take a handful of exposures. Other situations call for a more liberal approach to the number of frames exposed. But even then the seasoned pro is taking an active approach to controlling the things he can control so that when the "decisive moment" happens in front of him the shot will be nailed. When it was often suggested that his teams benefitted from far more than their fair share of good fortune, an iconic American college football coach used to be famous for saying, "Luck is what happens when preparation meets opportunity."
The pro usually discards shots not because they are so improperly exposed as to not be salvageable or because they are totally blurry due to poor camera handling or poor use of the camera's AF system. They are discarded because they're not quite as good as the shots that nailed the moment. Many of the pro's discards may be good enough for some non-pros to include in their keepers.
The pro knows how to setup the AF for a specific situation to increase the chances the AF system will select what he wants instead of what he doesn't want. Sure, AF is not perfect and will occasionally miss a little. But most mis-focused shots are missed because the photographer allows the camera to focus on something other than his intended target.
The pro knows how to read the situation and choose the best exposure/metering mode to maximize the chances that either the camera's metering system will give the desired exposure or that his manually chosen exposure will be correct.
The pro puts himself in the best spot to get the defining shot by actively thinking about how his position will impact the composition. If it's sports, for example, he anticipates where the action is going. He won't "hit" every time, but he will hit more often than someone just standing in the same spot and hoping the action comes to him.
When the pro gets an iconic shot, he understands how he managed to grab it and can reproduce that shot consistently when the same situation presents itself. Many time the amateur proves that "even a blind squirrel finds a nut every once-in-awhile."
In all of these areas, the key difference between the true pro and the less than professional amateur is the experience gained by learning from past mistakes and developing strategies to overcome the obstacles that led to that mistake. It is the lessons learned by examining the best work of the masters of the genre and actively analyzing how those images were captured and produced. It is the active planning, well ahead of the shot, to bring a specific vision to fruition.
Do most amateurs take the time and effort to do the learning away from the camera by reading articles and books by accomplished pros? (As an aside, too many of the articles I see on the internet seem written by people more interested in becoming known as a writer of internet photography articles than as a producer of quality photographs.) Do most amateurs spend as much time as a pro shooting a vast variety of subjects and situations, including many they aren't particularly enthusiastic about? Do most amateur photographers spend a lot of time after the fact self criticizing and reviewing their work as a means to constantly evolving and improving?
Can the amateur do any or all of these things? Of course the amateur can! But most don't.
