What different between near future in simple present and present continuous?

Answer 1

It's not really about near or far. We use the present simple for the future when we're talking about timetables, things like planes, trains, movies theaters, school and university. Some examples:

My flight leaves at 9 pm

My class starts in 5 mins

My retirement starts in 2 months

Etc

The present continuous or better, the diary future, is used for planned futures that have been arranged, organized, booked etc. Some examples

I'm going on holiday next week. (hotel's booked, tickets paid for and so on)

I'm having lunch with my mother next week. (I called her, we have arranged to meet etc).

If you remember it as the 'diary' future then these would be things you'd put in your diary because they would be things that were definitely going to happen, in contrast to 'going to' future which is used for intentions.

Answer 2

In simple present, we use "will" for future events that are planned or scheduled, while present continuous is used for future events that are arranged to happen soon or in progress currently. For example, "I will go to the beach next weekend" (simple present) versus "I am going to the beach this weekend" (present continuous).