“Will do” or " Be going to do"
I've learned from the grammar book that "will do" is normally used when sb decides to do sth just at the time he's speaking or when we're trying to predict the future; while "be going to do'' is applied when we've decided to do before we speak or when we 're predicting the future, or we're predicting what'll happen based on the current situation.
So, there's an example below:
I will go to the U.S next year to study for an MBA degree.
But, in this case, it seems '' I'll do sth'' is a plan, while ''will'' is not usually used in sth has been planned or decided, but to apply in predicting future happenings or situations. Is it because there're still one year, going to U.S is not so sure, or "will" is generally less certain than "be going to" ?And sth like studying abroad should be serious and this guy should has thought long about it. This would not be something he just decides to do when he speakes, but something he has already decided before.
If this example is right, then what's the difference between '' I'll go to '' and '' I'm going to do'' in this case.