Are there actually battles where it's like Finns vs. Russians, or Luftwaffe vs. USAF...or is it in every game mode just two teams with every player picking plane he wants?
Arcade battles: Mixed nations with arcadey flight physics, air spawn, small and kinda unrealistic maps and respawn with another plane after death.
Historical battles:Realistic setup like Germany vs USSR on semi-realistic maps with less arcadey flight physics. No respawn, take off at airfield, reammo only at airfield.
=> You can play realistic setups, but then also play a more realistic gameplay, which is in my opinion more fun than arcade anyway.
Ah and there is also "Full Real Battle", for the joystick people that want realism, cockpit cam, a bunch of additional options etc. Also with realistic setup of nations of course.