"The Earth has a North Pole and a South Pole."
Translation:Die Erde hat einen Nordpol und einen Südpol.
When do you use "die Erde" to refer to the world, and when "die Welt"? Or is there no difference?
Usually "die Erde" means the planet as a concrete physical thing, and "die Welt" means the abstract concept of everything happening on the planet, pretty much like "earth" and "world". Sometimes the two are used synonymously, but in this case we're talking about the physical places of North and South Pole, so it's "Erde".