Most people know what melody means. Some people even equate it with harmony itself. However, in the strictest musical sense, these are two very different things with very different purposes. If you want to learn what the difference between melody and harmony is, then read on for a basic introduction to two of the most important elements of music theory.
A melody is basically the one which dominates the whole musical phrases or sections of a song, while the harmony of a song is the one that’s used to complement the melody. Think of it this way: A melody is like your tee-shirt, and the harmony is the print, design, and colors of your shirt. However, this doesn’t mean that a plain melody without the harmony is boring in itself. Just think of how many shirts are ruined because of bad designs and colors. This means that a melody can be pleasant with or without a harmony. On the other hand, harmony is used to heighten the effect of a musical phrase/section. Think of how many good shirts look even better because of their cool print designs.
Melody: The Basics
To further understand what the technical differences are between a melody and a harmony, you have to understand what each one is first. As cited in the previous paragraph, a melody is the main series of notes that basically stand out. For example: the melody of a Happy Birthday song is easily recognizable. Its melody is simply the one that you sing (the lyrics). To choose another example (and to be a bit more technical), imagine a song in the key of C in a 4/4 measure. With this, a common example of a melody would be a series of notes that’s made up of C, D, E, G, A, G, and back to C, in that order.
Using Scales for Melody
Most musicians will recognize the previously mentioned group of notes as a pentatonic scale, in the key of C. Pentatonic scales are the most common group of notes that are used as a melody for a song. A musician can basically reorder these notes (or add some more) to form variations of the melody as the whole song progresses. The pentatonic scale is just one example; there’re certainly other scales out there that you can use to create melodies from, such as the basic Major Scale. In the key of C, the group of notes in the Major Scale would be C-D-E-F-G-A-B.
Harmony: The Basics
A song can still sound beautiful even without a harmony. However, if you really want to heighten the effect of particular sections of a song, then your best option is to use harmonies. Harmony is basically the complementary notes that you hear alongside the melody. Think of an A Cappella group of four people wherein they sing in different pitches (soprano, alto, tenor, or bass). Or, think of a high-pitched voice of a woman, and a lower-pitched voice of a man. Imagine both of them singing a song and complementing each other’s vocal parts. Duets like this are usually sung with harmonies, and not with octaves (octaves are just higher/lower forms of the same note, like lower-C to higher-C).
To use harmony, you only need some knowledge of scales to guide you. As mentioned before, you can use basic Major/Pentatonic Scales. The numbering system is useful in this method. The Major scale is always the reference to the numbering system of the notes C-D-E-F-G-A-B. Translated, they would be numbered as 1st (C-note), 2nd (D-note), 3rd (E-note), and so on. In the key of C, the number 1 is the C-note, and its other contrapuntal (or harmonic) notes would be the 3rd and 5th-notes (E and G).
Though it’s basically defined a little differently, counterpoint is actually related to harmony. Always remember that the most common starting note to use as a harmony is its contrapuntal notes of 3rds and 5ths. There are other counterpoint species you can use, but these are the most basic. On a guitar, when you see the chord C9, that means that you must add a 9th-note (or 2nd-note) to emphasize a harmony or counterpoint within that section of the song. The harmonizing 9th-note is the same as the 2nd-note, by the way (key of C, with a contrapuntal D-note on the C-chord).
To sum it all up in basic terms, a harmony defines a melody. But a harmony, by itself, becomes a melody.