Chords exclusive of the three primary triads, are usually called secondary triads. They enable the creation of more complex chord progressions—that is, chord progressions that use a wider and subtler range of colors than the strong primary colors of the tonic, subdominant, and dominant triads. Having the minor key more triads than the major key, the minor key can offer some really interesting chord progressions.
Triads Major Key
Triads Minor Key