They're based on the same pen and paper role-playing game, so the broad strokes (clans, general setting, atmosphere, etc) are the same. If anything, Bloodlines is closer to the P&P game in terms of the actual mechanics.

They both take liberties with things like disciplines to make them more suited to a computer game, so they can differ a little between the games in terms of the actual powers granted at each level. But again, the broad strokes e.g. Celerity = quickness, Thaumaturgy = blood magic, etc are the same.

You should know that the first half of this game takes place in medieval times and is based upon the Vampire: The Dark Ages RPG, still they're both in the same continuity though!

In terms of gameplay, in Redemption you have to fight a lot. In BL you have more social options, specially if you play as a Ventrue, which I would recommend for your first playthrough unles you really really want to play something else.

In BL; Toreador is another social play thru and doesn't have the killer discipline that Ventrue's have (suicide/mass suicide) so one has even less non-social to work with.

The main difference is basically their age; Redemption is more linear in concept as that's all the engines of the day could handle and the controls aren't as smooth. Both play lip service to White Wolf pen/paper games and books and clans are thus similar. I enjoyed both even with finding Bloodlines before Redemption.

Through an SDK, Redemption has a much higher capability in the form of making less linear custom quests and closer to PnP mods. Unfortunately, the SDK has quite a learning curve, but there are video tutorials at e-mods.net. And no... the SDK is limited and wont let you turn the game into an FPS. What the SDK does have are tools that allow building custom quests in custom made environments, making new disciplines or altering existing ones, building custom items/weapons/armors/npcs/players, and adding new game rules with some gameplay mechanics. Much of these things require robust Java scripting using the old 1.1.8 Java SDK with no means of plugging in an updated Java or any other language. Building new models requires MilkShape 3d, but unfortunately does not support making new animations. Redemption has yet to find someone technical enough to build an animation import/export plugin for any modeling tool. Again, there are tutorials on Java at e-mods.net with some pre-made scripts that will get anyone started making new quests.

Linearity can never be explained technologically, this is especially proven by the amount of non-linear early RPGs (heck, as far as I'm concerned RPGs only became linear by default in the 90's - not to mention that one year before Vampire there was Outcast, featuring a *huge* world with lots of optional content and many underlying mechanics). And Redemption itself is actually divided into hundreds of areas of different sizes, connected in a non-linear manner and they remain accessible most of the time except for a few points of no return (like the skip to the modern ages), it could have easily supported a non-linear campaign and side quests in technological terms.

In another thread, you asked if anyone knows the inner workings of the game; that would be the person above you (Javokis).