Found another difference:
1413 version has launcher, which allows you to use OpenGL rendering mode, which doesn't render glass, boxes in Lucky Ganesh shop and it also seems you can hold forward during loading screens. IIRC you can't do that in default D3D as the game will ignore the input.
I will test it more.
Add to that: in 5021 people will fall down when you shoot them but don't kill them, instead of just flinching.
Loading times in 5021 seem to be longer than in 5020.
In my 5020 PB, with one time where I loaded a quicksave, the difference between RT and IGT was 20:58. In my 5021 PB, single segment, the difference between RT and IGT was 21:15.
Other difference: In 5021 it's possible to make the alarm in your cell go off immediately without having to wait like in 1413.
Patch 5100 added the day selection from the main menu, you can now submit ILs for all the 5 days, please read the rules and good luck!