Future: I will or I’m going to … ?

Future: I will or I’m going to … ?
Differences between I will and I’m going to

Timescale:
-NOW (today)————–Few days after —-Exam-Future
1-I’ll work hard for my exam.->->->->->->->->
2–>-> -> ->-> ->I’m working hard for my exam.->

1: I take the decision: I’ll work hard!
2: I’ve taken the decision (1): I’m going to work hard.

Peter is at the hospital. I’ll visit him. (I don’t know when, but I want to)
Peter is at the hospital. I’m going to visit him tomorrow morning.

WILL:
FUTURE FACTS are CERTAIN, It’s sure:
WILL (we are certain to be true about the future!)
I’m sure she’ll like you. I’m certain you’ll love her.
I’m certain you’ll do a great work! My wife won’t be very happy. I’m very late.

FUTURE FACT are LESS CERTAIN, We are less sure:
WILL + I hope, I think, possibly, probably. (to show we are not sure)
I hope you’ll visit me if you come in London.
I think I’ll visit him to the hospital next week.
She’ll possibly come if she can.
He’ll probably come if he have free time.

GOING TO:
FUTURE FACTS based on a present evidence/situation? GOING TO:
The traffic is terrible today! I’m going to be late.
Look at the clouds. It’s going to rain, take an umbrella.
Look at the queue! We’re not going to get our tickets.

FUTURE FACTS are depending on your decison? (No evidence in the present):
You’re making the decision? « I will … »
You’ve made your choice? « I’m going to … »
I’ll visit him next week if I have free time. (I don’t know yet)
I’m going to visit him next week, I’m off on Monday afternoon.

WILL and GOING TO (both):
FUTURE FACTS, SITUATIONS, HAPPENNING in the future
(No dependance with a present situation!):
I think it will rain soon. / I think it’s going to rain soon.

IMPORTANT:
If there is a relation with a present situation, we use « going to »:
Look at the clouds: it’s going to rain. (prediction from a present situation).

ENGLISH FUTURE: