It's useful to think of relative major and minors as the same notes or chords but with different starting and end points. For example, C major and A minor are reciprocal relatives to each other, both key have the same notes and chords, in this case, all natural notes. A C major scale is C through C natural and an A minor scale is A through A natural, the same notes but with different starting and end points.
It's also useful to learn to identify the relative minor key and scale contained within the major key and scale and the reverse. (the major key and scale contained within the minor key and scale)
If you play a two octave C major scale for example, the A minor scale is the same notes beginning on the sixth degree of the scale and going past the octave to the thirteenth and if you play an A minor scale in two octaves, the C major scale is the same notes but beginning on the third degree of the A minor scale and going past the octave to the tenth scale degree.