We use will for: future predictions based on what we think orimagine. I think life will be better in 2100.* on-the-spot decisions. It's cold. I'll close the door.We use be going to for:future predictions based on what we see. Watchout! You're going to fall.future plans & intentions. Now that I've got themoney, I'm going to buy a new computer.We use present continuous for fixed arrangements.John's leaving tomorrow. He got his ticket.​