+1 (and repeating myself) that the perceived difference in the hubs is meaningless real world riding.

But, since I know that people are obsessive and can't leave well enough alone, here's things to consider.

1- The differences could be inherent in the design, such as a freewheel ratchet that's a bit stiffer.
2- Viscous drag from more or stiffer grease
3- Seal drag, from tighter or dry seals, or no seals on one.

4- Bearing friction, which is more complex, and which I mention only because others reference tightly adjusted hubs. This is tricky, because an improperly loose hub will have less friction when spinning in your hand, yet more once it's loaded with your weight. So, before you decide to readjust the bearings stop and think.

Spin the axle between your fingers, and feel the drag. Grease and seal drag are very smooth and silky (unless there's dirt contamination). Bearing drag from a tight bearing, feels "mechanical" with a sense of metal to metal contact and vibration. However, a properly adjusted hub has a bit of preload, because that's what the design calls for, and so you should feel it slightly.

Component makers set the hub bearings on the tight side for two reasons.
1- loose bearings are more of a problem, so they err tight. Also it's difficult to properly align a wheel if there's any hub play.
2- a hub adjusted to the tight side will wear to correct tolerance, whereas a loose hub only gets worse.

Without knowing any specifics and having the ability to see if there might be a problem, I repeat my earlier advice.

STOP OBSESSING and ride the bike.