Just reading the preview:
The biggest change over the Arma 2 series is in the armor. The armor system is completely different than standard Arma 2 engine. It counts several parameters, such as distance, speed of the shells, angle of armor, and thickness of the armor. The developers tried to make it as real as possible. Every tank has its own special hit points — ammunition, gun, trucks, turret, engine, and fuel. For example, you can hit a tank where there is nothing critical, and there will be no serious damage to it — except the shrapnel will injure the crew. But if you hit the fuel area, the tank will start burning. You can hit the ammunition storage and that will cause a total detonation of the tank, and will blow off the turret and other parts.