We use Will and Going to when we want to refer the future, but sometimas could be very confusing to know which one to use.
There is a slight difference between the two but in the most causes can be used with no differences in meaning. Even a native speake is going to understand you without problems
Will vs Going to: Uses
- Fast Decisions (For thinks we decide to do right now)
Example: I will buy a car
Example: I will help you with that.
Example: If you don't study, I will tell your mother.
- Refusal (When we refuse to do something we use Won't)
Example: I won't go to the concert tomorrow.
Example: Don't worry, I will keep the secret
Example: When you are planing something or decision was made before the moment of speaking: Im going to travel to Concepcion next weekend.
Example: When there are signs of something is going to happen.
I feel dizzy, i think i'm going to vomit.
Actually we can use Will and Going to make predictions.
We use will for predictions when we have no real evidence: It will rain tomorrow! (It's a feeling but i can't be sure)
We use going to for predictions when we have some real evidence: It's going to rain tomorrow! (You see a big, black cloud in the sky so if it doesn't rain i'll be very surprised)
I think it will tonight.
I think it's going to rain tonight.
Its 8:30!, I think i'm going to miss the train
Its to late!, I think i will miss the train