Verbs simple aspect Continuous(progressive) aspect Perfect and Perfect Continuous aspect

Prediction
The be going to and will futures can both be used to make predictions about the future.

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  be going to: the prediction is based on some form of evidence that exists in the present.
  

It is often used to predict what is about to happen but it can be used to predict something that is not in the immediate future:
Oh look! That car is going to crash.
That child eats too much. He’s going to be really overweight one day.

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  will: to express beliefs, hopes, thoughts, assumptions and doubts about the future;
  

It’11 be a difficult year for the new Prime Minister.
I’m sure you'll enjoy yourself there.
Statement of future fact
The be going to and will futures can both be used to make statements about the future but the emphasis is slightly different:

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