Form = will VERB, be going to VERB
The future simple is used to express that an activity, condition or something will begin in the future.
Sam is going to study at Harvard next year.
Max is going to retire in three years.
The simple future can be used to express a future plan using BE GOING TO.
Max will help you with your homework if you are having problems.
You're cold? I'll close the window for you.
The simple future can be used to express willingness with WILL.
It is going to rain tomorrow.
The meeting is pretty important, so Mary will be there.
The simple future with WILL and BE GOING TO can be used to express predictions.