I think where people get confused is 4WD, MFWD, of FWA. If my understanding is correct the first two have a transfer case and drive shaft to the front end and the last one (FWA) is usually hydraulic motors on each front wheel. If I am wrong please explain the difference.
A "4wd" is technically a large, articulated tractor with almost equal power to all four hubs of equal sized tire.
An FWA, or MFWD is technically a smaller frame tractor that supplies "assisting" power to the front hubs mounted with smaller tires at a typically 80/20 ratio or thereabouts.