Professional poker players are more dedicated and well-focused on the game or should we say that they have an advantage when it comes to experience. Anyone could play poker but not anyone could be professional in it. It needs a further understanding of how to deal with the risks of this game and having a sense of responsibility at the same time. People prefer poker over other gambling games because its risk is more manageable than others.
Professional means that they get money from the poker. It becomes a job. Of course they well-focused and more experienced players. And they get advantage the same as in any other job - their experience helps to analyze situation on the table fast and predict the next steps of the opponents. When the common player need time to think what to do, the professional make his bet instantly. The most interesting situation is when several professionals plays. In such situation they begin to think. When i understood how it works i stopped play poker - just sometimes $5-10 for fun.
It is not only more focused or experienced, I recently listened to an interview with a professional (female BTW) poker player. She spoke about the preparation and how professionals understand the game. One of the key things is that they will be playing 7 hours a day, mostly against a computer, exploring different strategies and "lines of game". It is becoming even more professional since the internet.
It`s the same as other professionals. They work(training) hard to get the result. And when we see it - no one think how difficult was to reach such results, often we even think "he makes it so easy, i think i can do the same".
Nowadays all professionals use computers in training - it gives huge opportunities. The poker and the chess are the main sports where the AI is the most useful for training i think.