There are a number of different minor scales available, suiting different situations and chord progressions. Two of the most common used by guitarists are the minor pentatonic (1-b3-4-5-b7) and natural minor scale (1-2-b3-4-5-b6-b7), also known as Aeolian mode. There are other scales, such as the Dorian mode (1-2-b3-4-5-6-b7), but the minor pentatonic and natural minor are the ones we usually learn first.
By contrast, the harmonic minor has a unique sound to it, which makes it rather appealing to the ears. The reason for this is that it features a major 7th interval (1-2-b3-4-5-b6-7), making it one note different from the natural minor scale.
