I just measured my thread and it's basically 13mm anyway. Maybe they've measured actual thread on one, whereas on the other they included the gap between full axle diam. and the threaded bit, which adds a mm.
Word of warning. Those removable levers get loose and rattle so I don't use them. I just carry a 5 or 6mm (whatever size it is) allen key with me rather than leaving the levers in the axles.
I just measured my thread and it's basically 13mm anyway. Maybe they've measured actual thread on one, whereas on the other they included the gap between full axle diam. and the threaded bit, which adds a mm.