Soviet tanks generally have thin armor, several vehicles do however have heavily sloped armor, increasing he effective armor. It also gives a higher chance for a shell to richochet. Their guns also pack the most punch in the game. They are the kings of close combat and are also fast and maneuverable. Their downside is that they have poor accuracy and aim time, in some cases they have a bad rate of fire, they are prone to ammo rack detonation and sometimes they are prone to engine fire.
Soviet light tanks are typically the fastest in the game and, like most Soviet tanks, have a small frontal profile and sloped armor.
Soviet medium tanks are also fast and maneuverable, but in order to make the tanks compact, engineers placed ammo storage in very vulnerable places, increasing the chance of ammo rack detonation.
Soviet heavy tanks have the best values for everything except accuracy and aim time; their frontal armor thickness and slope makes them quite difficult to penetrate from the front.
Soviet tank destroyers are not as well armored or accurate as their American or German counterparts, but they offer increased speed, agility, and brute firepower.
Soviet self propelled guns are generally quite accurate but don't do much damage. However, they also generally fire their shells in a very high arc, making their flight time long, but able to hit tanks hiding behind rocks and small buildings. They also tend to have higher firing rates than their foreign counterparts.
T-28E with F-30
Loza's M4-A2 Sherman
T-54 first prototype
Object 430 Version II
KV-220-2 Beta Test
IS-5 (Object 730)
Object 252U Defender
Object 703 Version II
Object 777 Version II
Object 279 early