If you hold a T20 bit next to a TX20 bit, the difference becomes obvious immediately.
This is the most dangerous question regarding these two fasteners. The short answer is:
If you're staring at your toolbox wondering if you need to buy a new bit,
is a frequent technical prefix used by certain brands (like Wera or Bosch) and in some European markets to denote the same 6-pointed star profile. Compatibility