ironglow i dont always agree with your opinions on religion or some other things but as to tanks you are the resident expert.
Not an expert, but just a guy who did serve as a tanker
many years ago, but keeps up an interest in armor developments. I expect those either recently or currently serving in armor can furnish much more info that can I.
The Russians use xplosive reactive armor..that is, when a projectile hits such armor...the armor explodes toward the projectile, hopefully either destroying the projo, or at least blunting it's force.
A note about reactive armor.. The Russians have a reactive armor..which is designed to explode outward
toward any projectile that hits it, hoping to destroy that projo, or at least blunting it's force.
The Abrams had Chobham armor (ceramic/steel layers..plus other secrets.).. Sometimes the Abrams will use reactive armor for special cases.
Our armored vehicles alsohave the benefit of the US/Israeli developed "Trophy" protective system, which explodes many and ordnance BEFORE it hits the tank.
One thing of note... tanks are normally accompanied by infantry, operating alongside. Since the Russians use explosive reacting armor, to have flat armor would mean that their own troops could be killed by the plates blowing outward. That is why the Russian tanks so often have those plates that are severely sloped..so the explosions are directed either upward or downward, rather than straight out, so they don't kill their own troops.
See the difference below.. since the Abrams either detonates the projectile far away or absorbs the projo, it's plates are flat..or somewhat sloped.
TOP..T90 Russian... Bottom, of course, Abrams..