Difference Between Dominant 7 and Major 7 Chords - Music Theory For Guitar

Tertian Chord Construction

First, you need to know that these two types of tetrad chords (major 7 and dominant 7) both belong to a family named tertian chords aka seventh chords. They are built by stacking four notes in thirds, thus giving a chord made of a root note (which gives the tonality of the chord), a third (which can be major or minor), a fifth (perfect, diminished or augmented) and a seventh (major or minor). This is how seventh chords are composed.

Dominant Seventh Versus Major Seventh

Now you know how seventh chords are built, let's see what's the unique difference between a dominant 7 chord and a major 7 chord.

Dominant seventh chords are made of a root (R), a major third (3), a perfect fifth (5) and a minor seventh (b7). Major seventh chords are built the same but the seventh is raised by a semitone, thus giving : root (R), major third (3), perfect fifth (5) and major seventh (7). The only difference is the seventh which is major (7) in major seventh chords and minor (b7) in dominant seventh chords.

In other words, these two types of chords are formed from the same major triad (1 - 3 - 5), on which a supplementary note is added on top. This note is the seventh, which can be major (7) or minor (b7).

Here below you see how the notes are stacked in thirds for each chord. Cmaj7 is built with a major 3rd +  a minor 3rd + a major third, whereas C7 is made of major third + minor third + minor third. Keep in mind that a major third is made of four semitones, whereas a minor third is made of three semitones. This article will help you learn interval names and their positions on the guitar.

Here are two basic shapes showing the difference on the guitar fretboard. You'll find mode complex positions on this website and also in the PDF Guittar Chord Dictionary available in the store.

Notation

Major seventh chords are abbreviated with maj7, M7, Ma7 or ∆. Dominant seventh chords are simply labelled with a 7. Example : Cmaj7 (C-E-G-B) and C7 (C-E-G-Bb).

Analysis & Harmonic Function

DOMINANT 7 CHORDS

Dominant 7 chords (represented in blue in the harmonized scales below) relate to the fifth degree of the major scale, the seventh degree of the natural minor scale, the fourth and fifth degrees of the melodic minor scale and the fifth degree of the harmonic minor scale.

The main feature of dom7 chords is the interval between the major third (3) and the minor seventh (b7). This interval is named tritone (it is made of three tones or six semitones). It is very dissonant interval and makes dominant seventh chords very unstable. Dominant 7 chords tend to resolve to the tonic chord (except in blues). Example with C7 that resolves to Fmaj7. 

MAJOR 7 CHORDS

Major seventh chords are more stable because of the interval between the major 3rd and the major 7th (fifth) which is more pleasant to hear. You'll find major seventh chords on the first and fourth degree of the major scale, the third and sixth degree of the natural minor scale, and the sixth degree of the harmonic minor scale.