Japanese animation theory. I could probably write a book on the subject, so I'll try to keep it down to the basics.

It's very easy for even a casual viewer to notice that Japanese animation has a different "feel" than American animation. Usually the difference is attributed to a divergent cultural viewpoint. What most viewers don't realize is how much it actually comes down to the physical differences in the technical processes.

To start with, on the cultural side, the main difference is that Japanese animation comes out of a completely different tradition of representation in art and performance. Western classicism is based on the strict adherence to realism, rendering the artist (and the process) invisible in order to elevate the subject. Classicist painting values the creation of an illusion. A painting should make the viewer forget he is looking at oil on canvas, and reveal its subject as if through a window on reality. Brush strokes must be blended so no trace of the artist's toil is evident. Western theatrical performance is likewise realist, defining a character through individuality, unique traits specific to period and setting. Japanese theatre and art, on the other hand, would fit the definition of "modernist" in Western culture. Asian painting is stylized, impressionistic (and expressionistic), concerned entirley with displaying the brush stroke and the flat, graphic nature of the picture plane. Japanese performance-- kabuki, noh, bunraku-- is similarly stylized, and more focused on capturing a distillation of character than emotional versimilitude.

This approach to representation carries over to animation. We can think of Japanese animation as an extension of Bunraku, using current technology. As in Bunraku, there is no attempt to create a seamless illusion of reality. The figures of the human performers can be seen manipulating the puppets. Likewise, the hand of the animator in Japanese aniimation is not only noticeable, it is often highlighted. (And this site seems curiously dedicated to cataloguing the signs to recognizing such individual animators' handprints.)

One reason why many young artists (including myself at one time) are attracted to Japanese animation and may be inspired to emulate it is that you can see how it is done. You can easily see it is composed of individual drawings, and for that reason, it seems within one's reach. In classical animation (I will call traditional Disney animation "classical" from here on), to allow the viewer to notice he is looking at a drawing is a cardinal sin. In classical animation, even held poses were traced over and over to make them "breathe". These are called "moving holds".

In classical American animation, the animator's hand must not be noticeable. The focus is entirely on the character and in the illusion that it is a living, breathing creature. From a Western animator's perspective, it is NOT praise to say "I noticed how well you animated that scene." That is a statement of failure. It means that the animation drew attention to itself. That is the basic violation of classicist representation in Western art, and of "classical" American animation. John Lasseter puts it clearly when he says he prefers the animation of Frank Thomas to that of Milt Kahl. You can tell a scene animated by Kahl. Thomas's efforts disappear into the performance, like a good actor's. That is THE major difference between Japanese animation theory and Disney.

Onto the technical side of things, here's just the start of a list of the main differences:

1. Looped as opposed to pre-recorded dialogue. Most casual viewers notice this right away. What's not obvious is how this affects the director's approach to staging dialogue scenes. The American director will focus on the character's performance as he delivers the dialogue, to the exclusion of other factors in a scene, such as environment, lighting, camera angle and movement, and other incidental details. The Japanese director tends to do the opposite. Both tendencies have their good and bad points. The evolution of most current Japanese animated character design derives from the need to cover the imprecision of their lipsync. It has resulted in the tiny mouths and tapered chins of so many "cute" lead characters, since drawing them that way allows animators to use fewer mouth poses and not to animate the jaw during dialogue. Spoken Japanese is made up of fewer phonemes than Western languages, so it also easier to get away with less precise lipsync.

2. Role of the director. In a lot of well-known cases (Miyazaki, Rin Taro, Kawajiri, Kon, Oshii), the kantoku draws the entire storyboard himself. The director is usually the kantoku, but depending on the individual, he might be a glorified scene checker, in which case, his job is called "enshutsu". For a time, a large number of Japanese animation directors started their careers not as animators, designers, or even storyboard artists, but as checkers (satsudashi). I'm not sure if this is true anymore, as the importance of the checker has been diminished by the transition to digital photography.

3. Studio organization. The division of genga and douga. (Genga means "original drawing". Douga means "moving drawing".) Apart from the Sakkan, that's all there is. Sometimes, the sakkan's role is so important that he may even be paid more than the director. The job doesn't exist in an American studio. The American feature animation studio is broken down into so many job categories, it is hard to keep them all straight. Supervising character lead animator, character animator, character assistant, character breakdown, rough inbetweener, inbetweener, lead cleanup, key assistant clean-up, assistant clean-up, effects animator, key effects breakdown, effects assistant and on and on. The most important difference is that Japanese animators are assigned sequences. They animate every element in a given sequence of scenes. Sometimes that includes characters, props, vehicles, machinery, animals, effects, shadows, backgrounds (if they move). American feature animators are cast by character. They will often have to "perform" with other animators on the same scene. The prince, the princess, the villain, extras, shadows, and any effects involved, will all be drawn by different animators, according to their specialty, even if they occur together in one layout.

4. Top pegs-- American animators bottom- peg their drawings onto a fixed pegbar attached to a rotating disc, which usually sits on a light desk tilted at a steep angle, like an easel. This enables them to use their free hand to "roll" their drawings as they work, which they do frequently to check the flow of motion. Japanese animators top-peg their drawings to a simple unattached pegbar which needs to sit on a near- horizontal surface. They flip their scene to check the action only occasionally, as they have to lift the stack of sheets up off the pegs. The Japanese animator is involved in a more mental (or intellectual) process, calculating the result in his head. The American animator is working more by "feel", or instinct, checking and rechecking it for fluidity constantly as he draws.

5. Exposure sheets- This one is very arcane, and its influence is tenuous, but I believe it is real. Japanese animators label their drawings according to which level they belong to. The 'A' cel is on the bottom, 'B' is second, 'C' is third, etc. American animators label drawings according to content. A drawing of a cat, for example, will be labeled 'C', and which level it occurs on the X-sheet will not change its designation. That character will always be 'C'. Japanese animators number their key drawings in sequential order regardless of how many drawings will ultimately be used to inbetween the scene. It is up to the inbetweener to change the numbering to the actual cel count when he traces the key drawings. I believe this system has been devised to make calculating cel counts easier, as it eliminates the possiblity of either gaps in the numbers or extra numbers, as in 5 1/2, or 5a, 5b, etc. For a key animator who decides to add a lot of rough breakdowns, this can result in a bewildering code for the inbetweener to decipher, as he must label the extra poses with katakana letters.

6. Pay calculation-- This has a huge impact on the entire approach to production in ways too arcane to explain fully to anyone who hasn't worked as an animator in a Japanese style studio. Key animators are paid by the cut (scene). Inbetweeners are paid by the sheet. It doesn't cost more for an inbetweener to spend longer on a drawing, resulting in a tendency to produce a lower count of very detailed drawings rather than a higher count of simple ones.

That's just the beginning of a discussion on the topic. I'll be happy to answer more specific questions as best as I can.