There's a pretty good summary of a lot of the positions here.
Original Creator
Director
Enshutsu (Animation Technical Director)
Character Designer
Animation Supervisor
Key Animators
Inbetweeners
Producer
Art Director (Art Model and Background)
Color Coordinator
Finisher
Special Effect / CG Artist
These are just a few highlights:
Original Creator (gensaku)
The original creator is the person who came up with the concept for
the story originally. This may be the original manga creator, a
novelist, game developer, playwright, author, oracle, prophet, or
whoever can come up with an original idea.
Enshutsu
Often translated as animation director or technical director. Enshutsu
is one of the most difficult and most important jobs in the Japanese
animation industry. The enshutsu is between the director (kantoku) and
the production staff. He is responsible for checking and supervising
the show through the production, from initial story to the final
released product, and in many cases, has almost total control over it.
He checks the animation drawings as they are being done, sets up the
scenes before they go to camera and supervises the sound and voice
recordings and all the editing amongst many other jobs. The exact job
and responsibilities vary from company to company, and from show to
show as well. Sometimes the enshutsu ends up as the whipping boy for
the director; sometimes he or she carries the show and the director
sits back and watches. On larger productions there is sometimes more
than one enshutsu and usually quite a few assistants. It is important
to have a good knowledge of animation production as well as artistic
talent to do the job and it usually takes four or more years in the
industry before someone can do the job right.
Inbetweening (douga)
The inbetweeners use the key drawings as reference points and produce drawings that fit between the
positions on the keys. This smoothes out the movement and makes the
animation look better. (The more inbetweens there are, the more fluid
the movement becomes and the more expensive the animation becomes.)
Inbetweening is a relatively non-creative job. It is more tracing than
anything else. The hours are long and the key animators are sometimes
very hard to work with. The cruelest part of being an inbetweener is
that they rarely get to work on anything they are fans of and what
they do get to work on they burn out on quickly. (I know some
animators and an enshutsu that you can send into convulsions by
whispering "Ranma" in their ears.) After 2 or 3 years of grueling
inbetweening, animators who can handle it are usually promoted to
keys.
As for a position that is present in anime production but not as common in western or traditional animation, I could could only find one position that might fit the bill.
Color Coordination (Iroshitei)
The Color Coordinator decides all the colors for everything that will
be painted/colored by the shiage department in the show and creates an
iroshitei hyou (color model pack) that the staff can refer to when
painting. This job requires not only good color sense but a good
memory, as the CC should be able to keep an idea of what the colors
for the whole show look like in her head so that when questions come
up about small details and things not in the iroshitei hyou she
doesn't need to pull all the models and think about it.
The CC makes
color models of each of the characters and the props, mecha etc. in
the computer paint system. The painters use these models when coloring
the various scenes.
In the old days of liquid paint, there were 327
commonly used Taiyou Shikisai (Taiyo Paint Company) cel paints but
they had over 1,000 in their catalog. Each color had a code number
which originally was its equivalent to the DIC (Dai Nippon Ink
Company) code. Color code numbers were usually a letter followed by
numbers like GY-40 and RP-99. (Some companies used another paint
company - Stack - but their paint was more expensive (and higher
quality) and the paint codes were different.)
A good way of telling
that you had done this job too long is when you lookout a train window
at a sunset or forest and find yourself determining what paint colors
they it is composed of. Computers have made life a lot easier with
16.7 million colors ending the need for weird paint codes but now you look at that sunset and wonder what dpi you would have to scan it in
to get good output quality.
I'm sure other types of animations have color coordinators but this one is somewhat specific to anime since it deals with a specific Asian company and their limited paint color selection.
The full page is worth a read as it has a lot of the Japanese names of positions in addition to their translated names.