ERA 3 armor changes (Challenger 1 & 2)

[crystal crown]

What exactly is changing? I see their guns/turrets/rotation speed is being buffed. But I am confused about the "improved effective armor"
Also, does this mean the Challenger mk3 will now have different armor values/effectiveness?

[thin ibex]

armor 1 , armor 2..... you never know which part, and you never know what exactly the modifier it is.