An interesting stranger is going to enter your life. OR
An interesting stranger will enter your life.
You are going to take a trip around the world. OR
You will take a trip around the world.
Use either be going to or will to make a prediction (a guess about what you think will happen in the future).
In some circumstances, however, it’s necessary to use one, be going to, for example, and not the other. Using the other expression, will, would be incorrect. Look at the waiter’s line below:
I’ll bring the appetizers right away.
Here the waiter uses a contraction of will (‘ll). He says I’ll bring because he has just decided, at the moment he speaks, to bring the appetizers. The waiter cannot say I’m going to bring the appetizer because it would mean that he had previously planned to bring them.
