Alexandrian and Gardnerian are the two more official forms of Wicca, and they are the closest to the original form of the faith. But many newer divisions have come about over the years, and Georgian Wicca seems to be a big search term here so I am going to go into a bit more detail on it.
First off, Georgian Wicca doesn't have anything to do with the state of Georgia. It was named after the founder, who's name was George Patterson.
Regardless of the origins, his form of Wicca is still popular today. He formed the first incorporated church in 1971, which is considered to be the founding date for this tradition.
His form of Wicca is very much like the older Gardnerian style, that you must be initiated into a coven and take an oath of secrecy about the practices. This path isn't considered to be truly Gardnerian because Patterson was unable to show a direct line of teaching from himself back to any documented Gardnerian covens. Hence the "offshoot" title.
Though the core of Georgian Wicca may be similar in practice to Gardnerian, there have been other eclectic elements included. Of course, I'd need to be initiated into a coven to get all the details, so I can't say much more than that because the information is not open to the public.
If you are interested, you can check out the Georgian Wicca website and get in touch with them directly. They can help you find a local coven to study with, or even contact someone for remote studies if no such group is around. They maintain a page on Facebook too if you want to see more about what they're up to as a community.
There aren't any books published on their ways, but they've said that the rituals in books like The Witches' Way or Eight Sabbats for Witches are similar. You can read those to get an idea what's involved.