The Circle of fifths, text table, shows the number of flats or sharps in each of the diatonic musical scales and keys. Both C major

C major

C major is a musical major scale based on C, with pitches C, D, E, F, G, A, and B. Its key signature has no flats/sharps.Its relative minor is A minor, and its parallel minor is C minor....

 and A minor

A minor

A minor is a minor scale based on A, consisting of the pitches A, B, C, D, E, F, and G. The harmonic minor scale raises the G to G...

 keys have no flats or sharps.
In the table, minor keys are written with lowercase letters, for brevity. However, in common guitar tabs notation, a minor key is designated with a lowercase "m". For example, A-minor is "Am" and D-sharp minor is "Dm").
The small interval between equivalent notes, such as F-sharp and G-flat, is the Pythagorean comma

Pythagorean comma

In musical tuning, the Pythagorean comma , named after the ancient mathematician and philosopher Pythagoras, is the small interval existing in Pythagorean tuning between two enharmonically equivalent notes such as C and B , or D and C...

. Minor scales start with , major scales start with