The terminology is: wheel ends by positions with powered distributed to.
So, 2wd truck is 4 wheel ends and 2 positions with power distribute to. Lockers/limited slips/dual rear wheels/central differentials/etc make no difference.
4wd is 4 wheel ends and 4 positions distribute power.
The tandem Ranger I am building is currently 6 x 2 - only the forward rear axle is powered as getting power to the aft axle requires some creativity.
6x4 truck usually has 2 rear axles powered, but powering the front axle and just one of the rear axles is another option.
Technically, an unpowered single axle trailer is 2 x 0. Most bicycles would be 2 x 1, but I have seen a 2 x 2 mtb!
I pine for the day that everyone will understand this.