- Organ sound does not fade. Because of the hammer mechanics, the sound produced by piano strings begins to fade as soon as the keys are struck. The organ sound, on the other hand, can last indefinitely as long as the key is depressed and there is a constant air flow into the windchest. "The monster never breathes," - once said I.Stravinsky, one of the most important 20th century composers.
- Organ dynamics are not achieved through the touch. While the dynamics on the piano can be produced by playing using more or less force, the sound on the organ can be made louder or softer using different means. The most obvious possibility for changing dynamics on the organ is by using various stop combinations. In addition, many organs have an enclosed division which has special shutters operated by the swell pedal. Opening or closing the swell division can also make the organ sound louder or softer.
- Organs with tracker action have a breaking point. Differently from the piano, mechanical action organs have special breaking point on the keyboard which arises when the pressurized air suddenly goes into the pipe. As the key is depressed, at one point the pallets which are located underneath the pipes are opened with a sudden movement. This action produces some sort of "spitting" sound of the pipe.
- Depression and release of keys are even more important on the organ. Since the organ sound can last indefinitely, organists must take great care to coordinate the attacks and releases of organ keys and pedals. The notes which have to be struck together must be depressed with absolute precision. On the other hand, in polyphonic music, the notes, which durations do not correspond, must be released exactly at the right time.
If you have previous piano experience and are trying to play the organ, a great resource is Organ Technique: Modern and Early by George Ritchie and George Stauffer.
You can also download my FREE video guide: "How to Master Any Organ Composition" in which I will show you my EXACT steps, techniques, and methods that I use to practice, learn and master any piece of organ music.