The Major Scale or Ionian Mode, has two notes that produce tension, they are the (2nd/9th) and (6th/13th).
[G-A-B-C-D-E-F#]

The Minor Scale or Aeolian Mode, has two notes that produce tension, they are the (2nd/9th) and (4th/11).
[E-F#-G-A-B-C-D]

As you can see both scales share the same notes, but they have different tension notes and target notes.
So you can use Relative Scales, only if you know, what notes you want to target, and which notes need to be resolved.

On the other hand... Jazz players use the tension notes in extended chords; to leave some sort of suspense hanging in the air.