Chord Theory: The Difference Between a 6 chord and Major 6th Chord

Major 6th versus 6th chords overview:

A Major 6th chord is: 

The major 6th chord is a maj7 chord with an added 6th or 13th. Usually functions as the I chord.

A 6th chord is:

The 6th chord is a major triad with an added 6th. Usually functions as the I chord.

Dominant chords with a 6th are: 

Dominant chords with 6th are called 13th chords. Usually functions as the V chord.

Question about 6th and major 6 chords:

Is there no difference between a 6 chord, which I guess would be a Dominant 6 chord and a Maj 6 chord? Is the Maj6 fairly exclusive to jazz?
In some other types of music I see chords called 6 which only have the 6 note added to a major, such as adding a B note to a Dmaj chord barred at the 5th.

Question by Craig Hedrick
(Belmont, NC, USA)

What's the difference between a 6th and major 6th chord?

In most contexts in jazz, the 6th ch

ord is a triad with an added 6th. You could write C6 as Cadd6 and it would mean the same thing. It is spelled C E G A.

Conversely, the "major" part of "major 6 chord" implies a major 7th. We would spell Cmaj6 as C E G A B.

The 6th and major 6th chords are often the I chord, functionally. 

Still not sure what all of this means? Check out the Beginner's Guide to Jazz Chord Progressions or get a handle on some basic jazz theory to find out more about what's going on.

Can we add a 6 to a dominant chord?

If we're talking about dominant chords, we are traditionally referring to the V chord functionally. If we have a 6th in a dominant chord, we would instead call it a 13th chord. 

Although the 13th chord technically implies the inclusion of every extension after the 7th (i.e. the 9th and the 11th), the 13th chord is often played without them. For C13, that would mean: C E G Bb A. In functional contexts, the 13th chord is usually a V chord.