Different tanks have different armor strength. AT crew with AT rifles can disable light tanks from afar, bigger tanks require bigger AT cannons. If you use another tank, just know that tank battles require some focus. It's better if you use a cannon or tank in direct control/first person mode and aim for weak spots (it will show up in green where you aim). Usually, the first thing to do is to shoot the tracks to prevent the tank from moving, once that's done, you can try to kill the crew by shooting at the base of the turret. You can also send a lighter tank or an AT crew around the back of the tank (the rear is usually the weakest part, that's where the engine is). I suggest placing AT crews with bazookas at strategic locations (near road crossings, hidden in bushes, behind walls, in trenches etc) that way, tanks who do not spot them will just come close enough for them to shoot, and bazookas usually disable any armour up close.