How are relative major and minor keys related?

Relative major and minor keys are fundamentally related by the fact that they share the exact same key signature and the same set of notes, despite starting on different pitches.1

Because they utilize the same notes, these keys are closely linked within the tonal system. The relationship can be defined by the following characteristics:

• Tonic Placement: A relative minor key always begins on the sixth tone of its relative major scale.1
• Interval Distance: The relative minor key is located a minor third (three half steps) below its relative major.1
• Visualization: The circle of fifths is used to map these relationships, with each minor key positioned in the same location as its relative major.2

For example, C major and A minor are relative keys; both have no sharps or flats in their key signature and consist of the same notes (C-D-E-F-G-A-B). In this pairing, A minor is the relative minor of C major, and C major is the relative major of A minor.1