What is the key difference between major and minor scales?

The distinction between major and minor scales primarily lies in their tonal characteristics and the emotions they convey. Major scales are generally associated with a brighter, happier sound due to their specific pattern of whole and half steps. This creates a sequence of intervals that tends to evoke feelings of cheerfulness and positivity. In contrast, minor scales have a different pattern of intervals, often producing a sound that is perceived as more somber or melancholic, which is why they are frequently described as having a "sad" quality.

Understanding this concept is essential for musicians and composers because the choice between using a major or minor scale can significantly influence the mood and emotional impact of a piece of music. Knowing that major scales convey joy and minor scales evoke sadness helps artists make informed decisions about their compositions and performances.

The other options present ideas that don't accurately reflect the fundamental characteristics of major and minor scales. For instance, the length of the scales is the same, both scales can exist in various meters and don’t inherently define their mood, and the number of sharps in each scale varies based on the specific key, rather than being a universal trait of major or minor scales.