What makes the Major-minor difference in music?
Maybe you are aware of dominant and tonic, the two solid navigational waypoints in the common scales. Above the tonic there’s a note roughly midway up to the dominant. This is the “hub”. We might learn this as a third waypoint. It is somewhat less solid, because it varies slightly (from one melody to another) to give the major-minor feel to the music.
The interval the hub makes with the tonic is a third. That interval is either four “frets” (semitones) or three frets. The four-fret third is a major third (M3), and the three-fret third is minor third (m3).
As a melody proceeds, the hub is usually sounded fairly often, and it resonates in the memory to give the major feel or the minor feel to the music.
Harmonically, the tonic chord, sounded quite often, reinforces the major or the minor feel. The tonic chord uses all three waypoints: the tonic, the dominant, and the M/m hub.