Simple Future Tense: will + infinitive

- for decisions made at the moment of speaking

A: It’s cold here.    B: I’ll close the window.

-to give your opinion about the future

 I think I will live in a big town.

Going to future : am / is/ are + going to + infinitive

-future plans made before the moment of speaking:

A: We have no milk.
B: 'I know, I'm going to buy some.'

-prediction based on the present:

Look at those boys! They're going to break the window.

There is a simple exercise for you.