Future tenses

[Toamaranthe]

Hello. I'm Amaranthe To.
I'm stucked among the future tenses:
-be going to.
-be Ving
-will V
-be to V
Can anybody explain to be about all the differences?
Thank you so much for helping me.
Amaranthe To

[Mister Micawber]

Excerpted from Michael Lewis's book on the English verb:

Be going to - The speaker has evidence, external (weather report) or internal (a plan) for the future event at the time of speaking.

Be Ving - The speaker is visualizing the durative action happening sometime between a point in the past (an arrangement) and a point in the (usually near) future.

will V - Modal. Given the current circumstances, the speaker considers the action a future fact.

be to V - Formal. Certainty about a future fact based on a formal announcement, authoritative decision, etc.

V (present simple) - Pure fact or simple truth or action determined by an external 'force majeure'

Note that these analyses are not available to the average native speaker, that much depends on the speaker's subconscious perspective on the event, and that the usages of these future forms overlap considerably.
_________________
Native English teacher at Mister Micawber's