The whole reward system in the game is divided into categories:
1) Effectiveness Points
2) Levels (Ranks)
3) Medals/Decorations
4) Achievements (Badges and Insignia)
Effectiveness points are given for different sorts of actions that you perform in the game: takeoff, landing, completing a mission, damaging or taking down an enemy plane, destroying a ground unit or bailing out, etc. This score depicts your virtual life in details. Playing on Hard difficulty setting grants you the option to earn more of them, Normal mode gives less. These points index your overall skill and define your level.
Skill level shows your advance through the game. Obtaining a new level grants you an ability to unlock new modifications or a plane, until you get them all. This entire development system is pretty much typical for most games these days, it's popular and simple. You decide what plane and what mod to use. We know that a part of the community only flies fighters and attackers, other guys only stick to bombers - the choice is yours, anyways we're sure that each aircraft that we put in the game will be a great machine worth your time and attention.
Players will have one rank indicator for all their profiles while these profiles may have different levels depending on pilot's progress in German and Soviet campaigns. For instance, you may see a Rank 5 player meanwhile his level on the USSR profile could be higher than on the German one, and it would be shown on his badge.