What's in your mind和What are you thinking about的区别

这两句都是问对方在想什么,前者更地道一些.还可以说：what's in your brain?或者what's going on in your mind?比如你跟人谈话对方走神就可以用啊~
问对方的想法应该用：what do you think?(相当于what's your opinion?）例如：Let's go to the theater tonight,what do you think?