Okay, I realize that there are a lot of wrong things with the question I posted so, to better describe what I'm talking about, this video explains it
https://www.youtube.com/watch?time_continue=351&v=av6PwZ78zKY
In the video the guy says that F is the subdominant of C and G is the dominant of C. This is correct but using the circle of fifths to explain this topic of music theory really isn't the most efficient seeing as it complicates things.
Look at it like this... Each major or minor scale has 7 notes. The first note of the scale will always be the tonic. The fourth will always be the subdominant. The fifth will always be the dominant
In order it looks like this in the key of C major.
1-2-3-4-5-6-7 = C-D-E-F-G-A-B
C = Tonic
D = Super Tonic
E = Mediant
F = Sub Dominant
G = Dominant
A = Sub Mediant
B = Leading Tone
That is what you call the names of the scale degrees. Basically this stuff really isn't all that important aside from being aware of the definition of Tonic, Sub Dominant, Dominant, and Leading Tone. The leading tone is the note that wants to resolve back to the tonic because it's only one half step away. (B & C) If you played the dominant chord of C Major which would G Major then the notes would be G-B-D. Notice how that chord contains the B or the leading tone? For this reason, the dominant chord wants to resolve back to the tonic chord.
This stuff really isn't as relevant or important as you think it is until you get into part-writing or counterpoint which is pretty advanced music theory.
So how does this relate to the circle of fifths? Basically if we choose any letter from the sharp side of the circle (#) the subdominant (4) will be the note behind it and the dominant (5) will be the note in front of it. Lets just choose the letter G. Well if we look to the letter in front of it we get D which is the dominant of G major. The letter behind it is C which is the subdominant.
Another relationship is that the closer the keys are on the circle of fifth the easier it is to modulate into them or mix into them during your DJ sets. The reason why is because the notes between a subdominant key and a dominant key are HIGHLY related and almost the same.
Notice The notes in G Major, C Major, and D Major.
C Major = C D E F G A B
G Major = G A B C D E F#
D Major = D E F# G A B C#
See how if we were playing in the key of G major it would be easy to borrow chords from the other keys? Theres only a 1 note difference between the keys Gmaj and Cmaj and also the keys Gmaj & Dmaj.
Music is based off the Major key.
Your Major scales eventually run into your minor scales as you progress up or down the keyboard. This is true for any instrument (absolute statement check me if i am wrong please).
I personally found the circle of fifths confusing as hell. All you really need to know is what i said above and how to play the scales. That's a REALLY basic understanding.
You're correct that the notes of the relative major and minor scales overlap. Not all music is based off of the major key though. There are songs which are clearly based off of a minor key and in that case the scale degrees change.
A natural minor key doesn't contain a leading tone. Look at this in the key of A minor.
A B C D E F G = 1 2 3 4 5 6 7
Notice how the notes G and A are 2 halfsteps apart? A leading tone needs to be 1 halfstep apart. That's why we have the harmonic minor scale which contains a #7.
A Harmonic Minor = A B C D E F G#
Notice how the G# and A are now one halfstep apart? Now we got ourselves a nice fat n juicy leading tone!
