I consider him to be a totally different person. I have added the vampire nobles to my save game. I prefer them over the vampires that are shipped with the game, perhaps because they feel more old fashioned and aristocratic. They moved in with Vladislaus Straud and share the house which is big enough for several vampires if you count the beds and coffins.
Elle De Vampiro and inna cents are not younger or different versions of existing sims so I never considered Vlad Bloodvein to be. Vlad Bloodvein looks like a tragic, sad figure who has lost the ability to enjoy life. He kind of reminds me of the movie 'interview with a vampire'. Vladislaus Straud is more Creepy and seems to enjoy being a vampire. That is how I see them at least. I don't know if this is exactly how the devs intended them.
But I did give Vlad Bloodvein a different first name so I don't confuse him with Vladislaus Straud
