Final answer:
The difference between a major and a minor triad lies in the interval between the root and the third; a major triad has a four half-step interval (major third) and a minor triad has a three half-step interval (minor third). Both triads have a perfect fifth. This difference changes the mood and character of the music.
Step-by-step explanation:
To tell the difference between a major and minor triad, you need to look at the intervals that make up the chord. A triad is a set of three notes that can be stacked in thirds to form a chord. Both major and minor triads are built from the first (root), third, and fifth notes of a scale.
A major triad consists of a root note, a major third above the root, and a perfect fifth above the root. This means that there are four half-steps (semitones) between the root and the third, and seven half-steps between the root and the fifth. For example, in a C major triad, the notes are C (root), E (major third), and G (perfect fifth).
In contrast, a minor triad has a root, a minor third, and a perfect fifth. This results in three half-steps between the root and the third, while the interval between the root and the fifth remains seven half-steps. An example of a minor triad would be an A minor chord, which has the notes A (root), C (minor third), and E (perfect fifth). Understanding these distinctions is essential both for performance and for music theory analysis, as the quality of the triad (major or minor) contributes greatly to the mood and character of the music.