In the books, Klaus was an Old One, while he was an Original on the show. He didn't have a family, so there was no Esther, Mikael, Freya, Finn, Elijah, Kol, Rebekah or Finn. There also was no Marcel either. There was no Doppelganger storyline in the books. Doppelgangers did not exist. In fact Katherine and Elena were actually half-sisters and there was no Amara or Tatia in the books. Julie Plec came up with the lore and backstory of the Doppelgangers. Honestly, TVD books is so much better than the show in my opinion, don't get me wrong I still love the show but I just prefer the books a bit more now after having reread them. Plus, I do kind of wish that Julie would have stayed close to the source material rather than make up her own lore and storylines and just slapping the book title onto the show. To me it screams disrespect to the original author of the books.