The original minor scale is part of the diatonic scale. It starts from VI and uses the same notes as the major scale.
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However, this scale ends with a Tone, meaning the VII note is the subtonic (a whole tone below the tonic) instead of the leading tone.
The harmonic minor scale is the natural minor with the VII note raised by a semitone to become a leading tone.
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This means it no longer has the same distribution of tones and semitones as the diatonic scale.