There's no real distinction between who plays what since the music was dubbed and remastered in final stage (meaning music editors add/remove sounds). Here is a link that explains their role(s): http://www.allmusic.com/album/memoirs-of-a-geisha-original-motion-picture-soundtrack-mw0000351871
Also there's a youtube link showing the process of the music in memoirs of a geisha - you can see how they are added.
If you wan't I can go over and listen to the album/score again...