Will you go...? or Are you going to go...?

Which is correct:

Will you go on a picnic tomorrow?

or

Are you going to go on a picnic tomorrow?

.Ooopss.

Hello, Isa.

Both are correct, and the meaning is exactly the same. The second one is perhaps a bit more natural sounding.

Hi Isa,
As Skrej said,both are correct.However,there’s a subtle difference between them !
We use “will” when we decide to do smth at the time of speaking(not before):
-Let’s have a party.
-That’s a great idea.We’ll invite lots of people.
But we use 'be going to" when we have already decided to do smth:
-We have decided to have a party.We’re going to invite lots of people.
-That’s a good idea.
Best wishes,
Morteza