Future with be going to and will

She is going to travel to America

He is going to sign up for an English course

They are going to get married

We are going to have a picnic

I am going to go to the beach with my family

Subject + am/is/are + going to + Verb

I will make a cake for her

We will go to the park by bus

They will not buy a car

I won't buy a computer now because it's too expensive

intension, plans, prediction based on evidence => be going to

Example: We are going to go to a concert on Friday (plan)

Example: Look at the sky. There're a lot of dark clouds. It is going to rain

Immediate decision, far future prediction => will

Example: What would you like to drink? I don't know, I think I will have some orange juice

In the future, people will travel by flying cars