Tilt changes the daily solar path
The rotation axis is tilted by about 23.4° relative to the orbital perpendicular. A hemisphere tilted toward the Sun receives a higher midday Sun and a longer daily path above the horizon. The other hemisphere experiences the reverse.
A polar day is a complete daily circuit
Near the summer pole, the Sun’s daily path can stay above the horizon throughout a full rotation. Near the winter pole it can stay below it. Enter 90° and −90° in the daylight calculator at a June solstice to compare these two cases at the same instant window.
Distance alone does not explain opposite seasons
Both hemispheres share nearly the same Earth–Sun distance on a given date. A distance-only seasonal explanation would not reverse their seasons. The useful comparison is solar altitude plus day length at paired northern and southern latitudes.