Inside of the Dome and Outside of the Dome
Think of the two most disparate locations you can think of… the two most radically different places you've ever been to. Now multiply those differences by a thousand, and you're close to understanding the gulf that divides the world inside and outside of the Dome.
The world(s) of Fuse is based somewhere in America —using context clues, we can infer that it's located somewhere near Maryland and Washington D.C. (After all, the main characters easily get to an airship located in the Capitol Building.)
But inside the Dome is where people called Pures live. Most children born in the Dome end up attending the academy and are genetically coded to become super-children, while the adults pretty much eat bon-bons, get massages, and sleep on feather beds.Oh, and it's run by an evil dude named Ellery Willux.
Outside the Dome encompasses the whole world, but Fuse mostly deals with the area around the Dome (although we get a quick trip to the Emerald Isle). We travel through places like the Meltlands and the Drylands, which are just as horrific as they sound.
Fuse is also set during the wintertime, which makes survival much harder for those outside the Dome: snow is everywhere, and you don't have shelter you're pretty much done for. It's a cold, dark world outside the shelter of the Dome… but being frozen and beset by Dusts still beats being spoon-fed lies by the Dome's government.