Yes the two definitely both bring something new to the table but their distinctions are not black and white which is what I find so interesting. ATLA was a lot more varied and content-rich I find (just consider the episode with the Guru and the profound references to Hindu Religion for instance. It had a lot more literary weight than LOK does now) however it never really explored its themes to their fullest extent - besides Zuko's internal struggle - because it always had to move on to the next thing.
Aang's difficulties with earthbending lasted only an episode while Korra's airbending troubles are a central theme. Same for - like I said earlier - the theme of government oppression which is briefly dealt with in Ba Sing Sei, but now really explored in LOK especially with what's happening with Tarlok.
But while LOK takes more time with its themes, its plot is also much more fast-paced. ATLA took its narrative pacing a lot more slowly, which several tangents and progressive developments. The main antagonist is not even introduced until the final book. Yet with LOK there is a new big revelation or major event almost every episode.
Those are just a few distinctions I see that are worth mentioning. I love how they decided to take such a different direction with Korra because comparing and contrasting the two different worldviews that the two series have is really rewarding I find XD
Aang's difficulties with earthbending lasted only an episode while Korra's airbending troubles are a central theme. Same for - like I said earlier - the theme of government oppression which is briefly dealt with in Ba Sing Sei, but now really explored in LOK especially with what's happening with Tarlok.
But while LOK takes more time with its themes, its plot is also much more fast-paced. ATLA took its narrative pacing a lot more slowly, which several tangents and progressive developments. The main antagonist is not even introduced until the final book. Yet with LOK there is a new big revelation or major event almost every episode.
Those are just a few distinctions I see that are worth mentioning. I love how they decided to take such a different direction with Korra because comparing and contrasting the two different worldviews that the two series have is really rewarding I find XD