What is the difference between general admission1and general admission 2. ??

General admission is general admission except for the front row I believe you have to have a special ticket so that might be the difference between the two but I think it's more than likely the gate one gate two thing as mentioned.

I believe the difference between GA1 and GA2 is that GA1 is tier 1, so those tickets will be sold first. Once those tier 1 tickets sell out, tier 2 tickets will start being sold at a higher price. (Someone please correct me if I'm wrong, I'm going off the top of my head and what I remember)