Certain things are based off the book, certain things aren't. But yes, they are different beasts.
I never liked people who became so anal over Stoker's book saying, "Oh, seeee, CV has to follow the novel's continuity because Bloodlines, so everything else is wrong!!!!!". People like that are so full of shit, it's running out of their nose. I just say it like this, if you cannot get over it and see that CV is it's OWN world, it's own history uniquely different from both Stoker's novel AND our real world history, you'll never be content with the games. I personally don't find it that hard to swallow or enjoy, be it pre-IGA CVs or IGA CVs. It seems like people that present themselves as historical scholars or literary scholars, quoting history and text, are the ones that become overly anal regarding CV's own history. Maybe because they thought that their knowledge would benefit in discussion, but they discovered that it's not as helpful as they thought it would be.