Betrayal Mechanic. Gravicious on Transport T3 vs T4 rewards

I know the obvious difference between T3 and T4 for Gravicious is 1 vs 2 boxes.

But can anyone from GGG confirm if there are any other differences? im wondering if T4 also have a better chance of getting the better drops or not.

There are no information out there for this, and everyone is saying conflicting things with no confirmation.