Originally Posted by: JoeNoviceHere are the facts.

Diatonic - a scale with 7 different pitches (heptatonic) that are adjacent to one another on the cirecle of fifths; thus, one in which each letter name represents only a single pitch and which is made up of whole tones and senitones arranges in the pattern the pattern embodied in the white keys of the piano; hence, any major or PURE minor scale and chuch mode (quoted from The Harvard Dictionary of Music)

First of all, I have always complied with the rules of the Guitar Tricks website, and in all the previous posts in this thread I have not insulted you, and I am not about to start now, I have no need to go down to your level, you called me "smart ass", and I understand that you insulted me due to your lack of intelectual capabilities.

According to the definition that you, yourself brought up,

Diatonic - a scale with 7 different pitches (heptatonic) that are adjacent to one another on the cirecle of fifths; thus, one in which each letter name represents only a single pitch and which is made up of whole tones and senitones arranges in the pattern the pattern embodied in the white keys of the piano; hence, any major or PURE minor scale and chuch mode (quoted from The Harvard Dictionary of Music)

we can see that the E Neopolitan Minor Scale is in fact a Diatonic Scale.
E major Scale..................[E-F#-G#-A-B-C#-D#]
Neopolitan minor Formula...[1-b2-b3-4-5-b6-b7]
E Neopolitan Minor...........[E-F-G-A-B-C-D]
As we can see this scale fits completely with the definition of Diatonic.
*It is a Heptatonic scale, because it has 7 notes.
*Its notes are located in the white keys of the piano.
Any Relative Scale to the Standard Major is indeed Diatonic, as in the case of the Neopolitan Minor.

Also, in the link that you so kindly provided for us,http://guitarsite.com/scales.htm,
we can see that the Major and Minor Scales are not the "Exact same thing"
Ionian.....[1-2-3-4-5-6-7].........2 2 1 2 2 2 1
Aeolian...[1-2-b3-4-5-b6-b7].....2 1 2 2 1 2 2
After seeing this, How can you say that they are the same thing?

Now in respect to the C6 chord, and the, Am/C chord.
This is the structure of a Major 6 chord:
(1,3,5,6)
(C,E,G,A)

And the Am/c, is a slash chord; basicaly an A minor Triad with a C note on the bass.
(A,C,E)/C

Your sarcastic remark in the comparison of those chords to the Major and Minor Scales is also wrong.
As it has been said before, the fact that the scales have the same notes does not mean they are the same thing.
To understand why the scales are different, you have to understand the basic principle of Intervallic Reletionship.
Here is an example of this in the key of A.
*[1-b3]=A-C
*[1-#2]=A-C
Both result in the same notes(A & C).
But the first is a Minor 3rd interval.
The second is an Augmented 2nd.
That is the principle that differenciate the scales.
And what are scales after all?...a progression of notes with fixed intervals.

I have layed out the facts, now it`s time to move on.