The last one (empire and Varden) can be compared to the stormcloaks and the Imperial Legion in SkyrimWell, I'm not going too in depth with detail, because I'm gunna do an actual huge writeup on it, with story backgrounds, etc.
But basically, there will, just like in Skyrim: the Companions, a Vampire Guild, the Dark Brotherhood, the Thieves Guild. And from Inheritance, there will be the Empire, and the Varden.