A scale goes from a note to the same note, but one octave higher. From C to C for example. We have divided this octave in 12 notes. Scales are only the notes you choose to play on your way from the root note (C here) to the higher root note (C again). Usually, in modes, you have 7 notes, including the root. C major (or Ionian) is CDEFGAB. C minor (or Aeolian) Is CDEbFGbBb. SO each mode has its set of notes. You can have 5 notes scales (pentatonic) up to 12 notes (chromatic) Less than 5, you have a chord or arpeggio.