Just like in White Wolf's rich, fantastical universe, Vampire: The Masquerade - Bloodlines features a complex set of political factions. As you play the game, you'll be pulled between the following sects, each of which has a unique (and pressing!) agenda.
Vampires who reject the rule of the Camarilla. The Anarchs once held Los Angeles as a "Free State" until the Camarilla returned prior to the start of the game. They still control Hollywood and some areas in LA.
A coalition of vampires formed in the late 1400s to protect all Vampires from detection by the mortal population. The Camarilla is the dominate sect in the vampire world, and controls most cities. They are very rigid and feudal, and though a good idea the organization is seriously flawed.
The Kuei-Jin, or Kindred of the East, are not truly vampires. They are a similar form of undead from Asia. The Kuei-Jin generally dislike European Kindred, but are not necessarily antagonistic.
A sect of vampires devoted to destroying the Antediluvians before they return. The Sabbat are organized in a mockery of the Catholic church with Bishops controlling Sabbat activities in each city. The Sabbat are sworn enemies of the Camarilla who they consider to be pawns of the Antediluvians. The Sabbat are highly violent and contemptuous of mortal lives. The Sabbat are also known as the Sword of Caine.
Vampires more than 13 generations away from the original, Caine. Regarded as a sign of Gehenna. Thin bloods are typically not under the protection of the Camarilla and are occasionally hunted for sport. Thin Bloods are not a true sect in the political sense, but more a broad descriptor for a number of young vampires.