A:
there is a HUGE difference,
1) Gear live uses google brand new android wear Operating system. While gear 1 or 2 uses samsungs Tizen OS.
2) Gear live would be supported for much longer since google pushes out updates to its software while samsung would likely not push out alot to the gear live.
3) The gear live (and any other android wear devices) are based around google's voice command system) EX: you can ask the watch almost any question and it would respond almost instantly.
If you are looking to get the gear live be understanding that the gear live and the lg g watch are only the first android wear smartwatches that came out. Some amazing things are in the works such as the Moto 360! round smartwatch and many more to come.
ps. I just ordered the gear live. { ;
anymore questions feel free to ask me