To ensure the battles are as historically thrilling as possible from xingwang's blog

Airplanes available at the start have been reduced in their combat abilities, meaning you’ll have to strive to research and develop new craft in order to excel in War Thunder. Twenty two new planes have been added in Update 1.37 though, so no doubt you wouldn't want to stick with stock planes for too long when you can fly around in a German plane with a 75mm tank-buster cannon mounted on the nose. 

To ensure the battles are as historically thrilling as possible, Gaijin have altered the flight and damage models of more than 70 planes. Not only that, but some have had their weaponry changed up. For example, you’ll now find the B-17 bomber carrying less payload than it used to War Thunder Golden Eagles . 

If you’re a bit confused on the main menu post-patch, it’s because the game modes have been renamed, apparently in an effort to ward off confusion in new players. Arcade battles are still Arcade, but Historical Battles are now Realistic Battles and Full Real Battles are now Simulator Battles.