All signs point to them simply being a group of high-fliers (literally and figuratively), being prepped for early leadership roles. There's no mystery prize being handed out here, such as an all expenses paid trip to Section-31, just accelerated learning leading to a better chance of receiving a 'prestige posting' upon graduation.
Though every cadet is expected to excel, the Academy also operates elite programs for its very best and brightest. Such schemes have been beset with problems, however, due to the intense pressure to succeed felt by the selected few. One such set was Nova Squadron—a group of cadets with expert piloting skills. In 2368, when a member of the squadron was killed during an unsanctioned maneuver during training, the other four members of the group conspired to cover up their part in the accident. Another, more wide-ranging elite group was Red Squad, whose members underwent extensive specialized training, but were unprepared for the realities of field duty when they were thrust into action. Their unquestioning approach to duty contributed to an attempted coup on Earth in 2372, and to the eventual loss of most of the team during the Dominion War two years later. Fortunately, such incidents are so rare that they have not undermined the wider mission or standing of Starfleet Academy and its many illustrious graduates.
The Star Trek Book