Novice players are typically new to a game or system, so most of their time spent playing is centered on learning the game mechanics and exploration. They may or may not have a serious interest in the game, and they may choose to end the game prematurely if it does not amuse them right away.
Expert players, on the other hand, are well-versed in game mechanics and have extensive background knowledge in games. More than likely, they will be more devoted to finishing a game in comparison to novice players. They may also focus on skill and ability enhancement, rather than just aimlessly exploring the game space.