am + ing
Arrangements with other people
going to + verb
Plans (Certain)
will/won't
Decisions (almost certain)
will/going to/am +ing
100

I ____ meeting my friend at the weekend.

am

100

He ____ going to go on holiday.

is

100

I think Bayern Munich ______ win.

will

100

I'm not completely sure. I haven't decided yet. I will play/am going to play/ am playing

will play 

(because he isn't sure)

200

My football team _____ playing football this Tuesday.

is

200

It is ______ ___ rain tonight.

going to

200

I don't know what to do tonight, but I ______ probably ______ compiuter games.

will ..... play

200

The meeting was scheduled. It's in my diary. They are meeting/will meet/going to meet for lunch.

are meeting

(because its a meeting between people)

300

We _____ __________ (eat) lunch together.

are eating

300

There is a lot of traffic. It ______ ______ ______ take  a long time to drive home.

is going to

300

He ______ get fit if he continues eating unhealthy food.

won't

300

When i'm older i decided that i'm going to be/will be/ am being a doctor. 

i'm going to be

(its a certain plan)

400

I made you an appointment with the dentist. You will see/are seeing/are going to see him on Tuesday at 2pm

are seeing

(because it's an arrangement with another person)

500

I need to buy clothes for a party. I will go/am going/an going to go to the shopping mall by myself later.

am going to go

(certain plan, by myself)