Differences between the novels and TV series:

In the books, her sibling Erik (spelled Eric in TV series) is older (three years), heterosexual, and attends Brown University; in the TV series, he’s younger (two years), a high school student, and gay.
In the books, Serena came Home from boarding school because she got kicked out for not returning for the beginning of senior year; in the TV series, the Fernsehen version of her sibling, Eric, attempts suicide, compelling Serena to return Home (in her junior year).
In the books, Serena’s parents are still married and her mother, Lilian, never spoke to Dan Humphrey’s father, let alone dated him; In the TV series, Serena’s mom dated Dan’s father, Rufus.
In the books, when Serena returns, she still wants to party and have things return to normal. In the TV series, Serena is focused on changing and becoming a better person.
In the book series Serena's middle name is Caroline while TV Serena's is Celia.
In the books, Georgina Sparks is a ex-girlfriend of Nate's from rehab who briefly met Serena in Sun Valley, while in the tv Zeigen she's a "ghost" from Serena transporter, van der Woodsen's past.
In the books, Serena left because her parents wanted her to and because she had sex with Nate, while in the TV show, she left because on the night she slept with Nate, she offered cocaine to a guy that she was fooling around with, and he died. The death was caught on tape Von Georgina, who had secretly set up a camera so as to film Serena having sex. Serena left due to fear of being caught and due to guilt.
In the books, Nate and Serena hooked up before Blair and Nate dated. The series state that they only hooked up at the wedding.
Serena's relationship with Dan is longer and Mehr serious in the TV Zeigen than in the books.

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