WOOKIEPEDIA:
G-canon is George Lucas Canon; the six Episodes and anything directly provided to Lucas Licensing by Lucas (including unpublished production notes from him or his production department that are never seen by the public). Elements originating with Lucas in the movie novelizations, reference books, and other sources are also G-canon, though anything created by the authors of those sources is C-canon. When the matter of changes between movie versions arises, the most recently released editions are deemed superior to older ones, as they correct mistakes, improve consistency between the two trilogies, and express Lucas's current vision of the Star Wars universe most closely.
T-canon, or Television Canon, refers to the canon level comprising the feature film Star Wars: The Clone Wars and the two television shows Star Wars: The Clone Wars and the Star Wars live-action TV series. Its precedence over C-Level canon was confirmed by Chee.
C-canon is Continuity Canon, consisting of all recent works (and many older works) released under the name of Star Wars: books, comics, games, cartoons, non-theatrical films, and more. Games are a special case, as generally only the stories are C-canon, while things like stats and gameplay may not be; they also offer non-canonical options to the player, such as choosing female gender for a canonically male character. C-canon elements have been known to appear in the movies, thus making them G-canon; examples include the name "Coruscant," swoop bikes, Quinlan Vos, Aayla Secura, YT-2400 freighters and Action VI transports.
S-canon is Secondary Canon; the materials are available to be used or ignored as needed by current authors. This includes mostly older works, such as much of the Marvel Star Wars comics, that predate a consistent effort to maintain continuity; it also contains certain elements of a few otherwise N-canon stories, and other things that "may not fit just right." Many formerly S-canon elements have been elevated to C-canon through their inclusion in more recent works by continuity-minded authors, while many other older works (such as The Han Solo Adventures) were accounted for in continuity from the start despite their age, and thus were always C-canon.
N-canon is Non-Canon. What-if stories (such as stories published under the Infinities label) and anything else directly and irreconcilably contradicted by higher canon ends up here. N-canon is the only level that is not considered canon by Lucasfilm. Information cut from canon, deleted scenes, or from canceled Star Wars works falls into this category as well, unless another canonical work references it and it is declared canon.
I know.
It shows Jabba as the unified leader of the Hutts 20 years before ANH, whereas in the books it shows the story of how Jabba comes to power just months/weeks before ANH. Oh well.
