The Basics: Future with Will :
There are two basic future tenses used to describe things that happen in the future. Besides these two there are some other future tenses which can be started on the advanced future tenses page. The first future tense is the future with 'will'. Use the future with will to talk about an event in the future that you have just decided to do, for predictions and for promises.

I think I'll go to that party next week.
The economy will get better soon.
Yes, I will marry you.


The Basics: Future with Going to:
The future with 'going to' is used to express events you have already planned in the future and your intentions for the future. We sometimes also use the present continuous for planned events in the near future.

She's going to attend university and study to become a doctor.
We're going to make the presentation next week.


Future with Will Structure:

Positive

Subject + will + verb

I, You, He, She, We, They will come to the party.


Negative

Subject + will + not (won't) + verb

I, You, He, She, We, They won't have time tomorrow.


Questions

Question word + will + subject + verb

What will he, she, you, we, they do?

Future with Going to Structure:

Positive

Subject + to be + going to + verb

I am going to attend the meeting.
He, She is going to attend the meeting.
You, We, They are going to attend the meeting.


Negative

Subject + to be + not + going to + verb

I'm not going to visit Rome next year.
He, She isn't going to visit Rome next year.
You, We, They aren't going to visit Rome next year.


Questions

(Question word) + to be + subject + going to + verb

Where am I going to stay?
Where is she, he going to stay?
Where are you, we, they going to stay?