are all used to talk about the future.
We use the Present Simple to talk about timetables.
Examples The plane departs at 14:20.
The meeting is on 6th December.
The train arrives at 5 o’clock.
We use the Present Continuous to talk about arrangements with other people.
Examples We’re having dinner in the hotel.
She’s giving a presentation at the conference tomorrow.
How long are you staying?
We use going to to talk about plans and intentions.
Examples They’re going to discuss the problem at the next meeting.
I’m going to start exercising next week.
Are you going to visit the Pearl Tower when you’re in Shanghai.