Here is why I think he is (comperde to the Tecktree Counterpart T-34-85):
T-34-85 has 12 shots/min., 1920dpm, 126mm pen and 160 damage with the 85mm Zis-S-53.
T-34-85M has the same gun, but 11,54 shots/min., 2076dpm, 144 pen and 180 damage. He has simply more damage and penetration with the same gun.
If you want to play the T-24-85 with 180 Alpha-Gun (85mm D5T-85BM), you got a rate of fire of 10 shots/min. and only 1800 dpm. If you play the M, you have higher dpm and/or higher Alpha. T-34-85M has also better hull armor, better gun handling, higher shell velocity and slightly better camo then normal T-34-85. Only advantage of T-34-85: +1 kph top speed (53 by M/54 by normal) and a better power to weight ratio.