How do I tell the difference between a diminished and an augmented chord?

Answer 1

A diminished chord, D dim7, consists of minor thirds only, d-f-aflat-b-(d).

An aug chord D+7 consists of major thirds only as in d-f#-a# (or bflat)- and c.

Answer 2

I would love to explain the theoretical difference between a diminished and an augmented chord :)

A diminished chord is a chord consisting of a root note, a minor third, and a diminished fifth (flatted fifth).

For example, the notes of a C Diminished Chord are C, E-flat, and G-flat. This chord has a tense and unstable sound.

An augmented chord, on the other hand, is a chord consisting of a root note, a major third, and an augmented fifth (sharpened fifth).

For example, the notes of a C Augmented Chord are C, E, and G-sharp. This chord has a tense and bright sound.

The difference between these two chords is that the diminished chord has a flatted fifth, while the augmented chord has a sharpened fifth.

Answer 3

First, we have to clarify that a triad is a specific type of chord composed of 3 different notes, and containing intervals of either major or minor 3rds. Diminished chords and augmented chords are both two different types of triads. The diminished chord, which appears naturally in a major scale (built off of the 7th scale degree), is made up of 2 minor 3rds stacked on top of each other. An augmented chord is made up of 2 major 3rds stacked on top of each other. As such, the diminished chord has a "darker", more minor sound while the augmented chord is extremely "bright" sounding. If you have already practiced identifying your intervals, then you will have no problem hearing the difference between augmented and diminished chords. Simply listen for either the major or minor third, and that will tell you which of the triads you are hearing. If trying to identify the chords by sight only, count the number of half-steps between each note of the chord. Remember that minor 3rds are 3 half-steps apart while major 3rds are 4.