KC-46A will have 'palletised seats' - airline seats sitting on cargo pallets. How does that work with passenger facility units (in-flight oxygen, lighting etc.)?
It seems that the windowless KC-46A is only FAA-certified for 58 passengers (or 114 for 'contingency' operations). Palletised bog, palletised galley, palletised passenger bags - it really is 'Guantanamo Bay' Class travel.
Compare that with 'up to 300' passengers in the A330MRTT - all in normal airline seating. Seat pitch in Voyager is much more generous than in most airliners, due to the fact that military passengers with their equipment need more space.