I was just looking at the Align website and the only difference that I see is that the 450 Pro Super combo has the torque tube tail drive. The 450 Sport Super combo is belt drive.
If you are new to rc heli's, it may be a good idea to get the belt drive tail. A reason for that is when you are hovering the heli around and you are coming down to land, lets just say that the wind picks up a bit and the tail rotor hits the ground. Well, with a torque tube tail, this impact with the ground is surely going to cause damage to the rotor blades but it will, almost certainly, add an immediate shock to the torque tube and slow it down at the same time that the motor and pinion are trying to turn the torque tube inside the frame. This immediate shock causes teeth to strip out and or break on the umbrella gears. These would then need replaced. Damage could also be done to the torque tube. This would also need replaced.
Now..if you had a helicopter that had the belt drive tail, like I do, if the same scenario happens...most likely you are just going to damage the tail blades because that immediate shock, as described above, will just cause the belt to slip inside the helicopter. Yes, it's possible and maybe probable that some teeth on the belt may strip out but a new belt is much much cheaper than a new torque tube.
A new belt for this 450 is only $7.99. A new torque tube is $13.99.
Now...on the other hand...the torque tube is well known to be more precise and more solid than a belt drive because the umbrella gears mesh together so well.
I guess it all just comes down to "what you want". I am certainly not a professional helicopter pilot, by any stretch of the imagination, so I will probably stay with belt drive tails for many years.
Good luck Kenny!!!