Doesn't traction control further blur that? Given that traction control is now required almost everywhere, and involves cutting power to individual wheels (Not like ESP using brakes), at what point does traction control cutting power to individual wheels or axles dynamically in a 4x4/4WD system make it an "AWD" instead?
Perhaps those vehicles that use 4x4 in the tradtional sense are such that you have to engage it and that effectively cuts also any traction control - and then you disengage for normal driving?
Traction control on an AWD system can be composed of power management (overall torque output), power distribution (how much power goes to each axle/wheel) and braking (slowing down individual wheels).
Traction control on a 4WD can only consist of power management and braking, because there is no way to vary the distribution (otherwise it would be AWD, not 4WD).
There are some systems that under certain conditions will switch from 2WD to 4WD. Those systems are NOT considered AWD and dont have the benefits thereof.
FYI, ESP (Electronic Stability Program) is just a brand term for an ESC (Electronic Stability Control) which covers both TCS and ABS. When people talk about "traction control" they usually mean the entire ESC subsystem.
I think part of why I consider them to be one and the same is because in the total absence of "true" 4WD/4x4 (approximately no one drives pickup trucks in Europe, I'm guessing that's where the true 4x4 still lives in the US) so the 4WD/2WD moniker has been used for 2WD/AWD as in "Will you get the 2WD or 4WD tesla is used somewhat sloppily?". It seems car manufacturers though are still careful not to call anything 4WD or 4x4 when it's not.
Perhaps those vehicles that use 4x4 in the tradtional sense are such that you have to engage it and that effectively cuts also any traction control - and then you disengage for normal driving?