what are you going to do?
你去那计划干什么?
where are you going?
你要去哪里?
如：
A:what are you going?[你要去哪里?]
B:I'm going to hainan.[我要去海南.]
A:what are you going to do?[你去那计划干什么?]
B:I'm going to swimming.[我要去游泳.]