After researching it a bit, there doesn't appear to be a definitive answer. None of the links you provided give one either.
Some claim AWD has a center diff. Some say it's the manual vs. automatic control of drive wheels and diffs. Some say low range makes it 4WD. What some people/companies call a "center diff" could ALSO be considered a transfer case.
in the rules that this whole thread is about, they specifically mention the transfer case as the requirement for a system to be 4wd.
That article has zero cited rules, or really any citations whatsoever, so I'm not sure what you're referring to.
Only thing I can say for certain is that the article claims 4WD = locking diffs, which is obviously not true.
In summary, I'm wrong but so are you so nanananabooboo
Edit: I was able to find this definition from NPS
What is the difference between a 4x4 and All Wheel Drive (AWD) vehicle?
True 4x4 vehicles have a 'transfer case' in the drivetrain that puts full engine power to the front wheels. All Wheel Drive, common on vehicles like crossover SUVs, relies on a 'differential' to send variable power to each wheel. AWD is good on level roadbeds in low traction conditions like snow. It is not designed to fully power the front tires in off-pavement rugged situations. For example, if the road goes up a steep hill and there is a lot of loose rock in the road, fully powered front wheels are needed to rotate strongly and pull the vehicle up the slope. AWD cannot do that very well and may fail.
This is the opposite of true. 4WD absolutely does not and cannot send all engine power to the front wheels and a AWD with center diff potentially can but probably wont. However they often do send a disproportionate amount of power to the front wheels, as necessary.