Avatar: The Last Air-bender was a great hit show that Nickelodeon aired during 2006-2007. It was about a young boy, Ang, being the avatar, or a person who can control all four elements: fire, water, air, and earth. He is also the last air bender and has been asleep for over 100 years. The Fire Benders have taken control of the world and Ang must stop them. In the show finale, he succeeds in dethroning the Fire Benders and is successful in bringing a new era of peace to the Bending world. The Legend of Korra takes place after Ang dies.
The Legend of Korra takes place almost 50-60 years after Avatar: The Last Air-bender. It has become very modern, with great improvement in the technology field. There are late 1800's cars and modernized parks and houses. The main place, where the Legend of Korra takes place, is Republic City and looks very similar to a New York and San Francisco mix.
So far in the Season the next Avatar, Korra, goes to the modern city, Republic City, to learn how to air bend because she knows how to bend water, air, and fire. At Republic City she meets a surprise; there is a group against bending, element bending is used in sports, and gangs rule the ghettos of the Republic City.
When I first saw the first episode, I was disappointed it had such modern devices in it. I would rather of had it like they did in Avatar: The Last Air Bender. And they did not say what happened between Ang or Katara or her brother. I assume they might reveal what happens between them as the series develops, although a story up hand would of been very nice. In the first five minutes they do reveal that they know what happens to Zuku's mother but they do not reveal it.....yet.