[tiniuclx]

Chapman Stick player here! The Harpejji has a very different tuning and technique. The melody side of the stick is tuned in fourths (like a guitar), and the bass side is tuned in fifths (like a cello). The Harpejji is tuned in whole steps, meaning the strings are much closer in pitch than they are on the stick.

The implication is that the technique used for the Harpejji is much more similar to piano: every note in a scale is played on a different string, and chords are produced by 'skipping' notes / strings. Whereas scales on the Stick are usually laid out using 3 notes per string on the melody side (exactly like the guitar), and 4 notes per string on the bass.