live takes much more concentration. Mainly because you can get a big advantage if you know how to read people. YOu can pick up many more ticks and tells
Big advantage of online is you can see many more hands per hour. But most of the time, live you will play against much weaker players, especially in a casino or back room of a bar. At least around where i live.
I would rather play live everyday if i could, but no casino is super close, and the back room games are so crazy and pretty high stakes. Worth playing, but not every day.