• You can use both 'will' or 'going to' in the future, but we generally use 'going to' to talk about our future plans:
- What're you going to do next weekend?
- I'm going to visit a friend.
• We use I’ll … (= I will) when we’ve just decided to do something. When we say ‘I’ll do something’,we announce our decision. 'Will' is used to:
• Make predictions:
- What do you think about the game.
- I think they'll win.
• Make promises:
- I promise I'll clean up my room tomorrow.
• React to situations and information:
- I can't find my keys!
- Wait, I'll help you.