Understanding scales becomes easier when you think about them as musical families. Some scales share DNA, while others evolve into entirely new musical cultures.
The Parent Scale
The major scale is the foundation of western music theory. Many western scales are built from this initial scale. We can think of the major scale as a "parent scale" as many other western scales share variations of the major scale DNA.
Same Root, Different Notes
The parallel scale is like your cousin. It stems from the same family tree (same note), but there are different genetics (notes) are not the same as the major and relative. Parallel scales stem from the same tonic note, but contain different scale degrees and interval structures.
Shared DNA
The relative minor is kind of like a sibling to the major scale. Same genetics (same notes) but mixed up into it's own unique flavor. Relative scales share the same exact notes, but begin from a different tonal center, creating a completely new emotional gravity.
Different Musical Cultures
Modes are your Greek family members from a different country. While we often think of them in relation to the major and minor scales, they have their own cultural influence. Modes come from the same parent scale, but each develops its own tonal flavor, mood, and musical identity.