The hack n' slash sequel has a lot more going on than a tiny mining town and a single dungeon. Torchlight II is broken up into several overworlds, connecting areas, dungeons, and towns.
The wide-open overworlds are more than three times the size of the largest levels from the first game, and play host to dungeons, quests, and random events like bandits holding hostages or injured merchants in need of help. Runic is talking them up to be much more interactive and unique than the open areas in Diablo II, for example, with notable landmarks dotting the landscape and many named minibosses to fight.
Overworlds are connected by passes, which are more traditional linear levels that present different, explicitly themed gameplay. Runic gives one example of a pass called the Path of the Honored Dead: an undead-heavy cemetery covered in oppressive fog with its own dungeon to be explored.
Dungeons are what you'd expect, with winding passages and a loot reward (and a portal back to the surface, thankfully) at the end.
Lead level designer Patrick Blank goes into much more detail at the Torchlight II site, and answers community questions along with art director Jason Beck as well.
Need even more Torchlight II action? Check out the races that inhabit the world.
Torchlight II is scheduled to come out later this year on PC. No console announcement has been made, but you have to think that versions are being worked on after the resounding critical and commercial success of the late-to-the-party XBLA port of the first game.