What makes this setting different?
What makes the Wilderlands different is it's purpose for existing is to let the characters conquer it or die trying. Other settings' purpose for existing is to form intellectual property that can be exploited through film, literature, comic books or video games. That's a huge difference.
Wilderlands characters aren't pawns of the DM. They're the ones running the show. That's where it's similar to Conan, not in an actual "Conan the RPG" type way. It's Core D&D where the characters are issued a challenge when they first roll up their characters: see how notorious you can become, for good or for ill, before this setting overwhelms you. Ultimate victory is in gaining a high enough level that nothing in the setting can adequately challenge you any more.
In that sense it's far more like the World's Largest Dungeon than it is like Fantasy Realms. But it doesn't have the train tracks that the World's Largest Dungeon has.
Basically, a typical Fantasy Realms or Greyhawk campaign consists of the following: "Some evil blah blah blah insert plot hook here blah blah boxed text." The characters all run off to conquer the evil or whatever. They gain some loot. They return to town, sell the +1 longsword so they can buy a +1 falchion instead. Head out again, conquer some more evil, get some more loot, return to town, sell their loot, get a new plot hook, and so forth. It's just episodic plot hook to plot hook. That's fun, I'm not knocking it, I enjoy playing those kinds of campaigns, but in my opinion they're death to DM because everything's so predictable.
A typical Wilderlands campaign generally starts the same way with "some evil blah blah blah insert plot hook here blah blah boxed text." But when the characters go off to address the plot hook they have to go through six wilderness hexes, one of which contain giant frogs that swallow one of the characters. If the characters blew it and don't have a ranger or druid they get lost and get slowly picked off by randomly encountered winged apes. If they manage to find their way to the plot hook/dungeon they conquer some evil just like a typical game but things are different again when they try to return to the town to sell it all. Once again they get lost and this time they end up in a town run by orcs. But the orcs don't kill them because the town is "lawful" even if it's evil. They try to sell their goods but the orcs are really just interested in ripping them off and, besides, no one is selling a +1 falchion anyway. The characters start to realize there's no real reason to go follow the "blah blah plot hook" anyway because there's plenty of adventure to be had and money to be made killing the orcs in this town instead. They go on a rampage and set the town up as their own little fiefdom. The DM looks at the map and figures out the power centers around the town and who would be threatened by the PC's fiefdom. These towns/cities ally against the PC's or demand the PC's pay tribute to them. The PC's by now too big for their britches, decide they're not gonna pay tribute to anyone, and a war starts. So on and so forth.
It's a different style of play that yeah, maybe new RPG-ers won't understand because it hasn't been popular for a long, long time. I've recently heard it described as "game-ism", which makes sense to me. It's about the game, not about the story.
I would strongly contest, however, the notion that there is no "greater" sense of politics in the Wilderlands. That is true of some maps, but not all. You must read the chapters with the map laying out next to you, so that you can see exactly where each hex entry is as you read it. If you do this with the City State Chapter, you'll see that there is a wealth of political intrigue to be had on that map.
The reason so much of the setting is evil -- towns and cities with evil alignments, that is -- is that characters are mostly good. Would you create a dungeon filled with paladins? Not likely. This is a setting meant to be conquered.
Anyway, that's just my two cents. Your mileage may vary.