(Arrangements)
The present continuous tense is used in talking about arrangements. (An arrangement is is a plan for the future that you have already thought about and discussed with someone else.)
I'm meeting my mother at the airport tomorrow.
Our grandparents are visiting us this Christmas.
Sorry, I can't stay after school today; I'm playing tennis with Jun-Sik.
My sister's going to the dentist tomorrow.
I'm not returning home for the holidays, so I can come to your party after all!
Are you doing anything on Sunday morning?
Do you know if he is going to the dance with Maiko next week?
Scheduled events
The present simple tense is usually used to refer to future events that are scheduled (and outside of our control).
Hurry up! The train departs in 10 minutes.
I leave Frankfurt at 5 o'clock in the morning and arrive in New York
at midnight the next day.
She has an appointment with the headmaster after school today.
There's no need to hurry. The train doesn't leave for another 30 minutes.
When does the meeting begin?
http://esl.fis.edu/grammar/rules/future.htm