How do tsuyogin and yowagin melodies differ in Noh music?

In Noh music, the two primary melodic styles—the strong (tsuyogin) and the lyric (yowagin)—are distinguished by their use of fundamental tones and the intervals between them.1

• Yowagin (Lyric Style): This style utilizes three basic tones (jō, chū, and ge) that are positioned a fourth apart. The movement between these notes is governed by specific regulations, similar to the approach to intervals found in 16th-century Western counterpoint.1
• Tsuyogin (Strong Style): This style employs different rules for its fundamental tones, which are placed much closer together than in the lyric style. In modern practice, the jō and chū tones are at the same pitch, while the ge tone is approximately a minor third below them.1

These melodic styles are further defined by various ornamentations and formulas, with the specific choice of combinations determined by the dramatic needs of the text and the music's position within the overall structure of the performance.1