Originally Posted by JDR13
Ok, I'll humor you and act like I need to explain it.
In the novels, Saruman was a legitimate third power in the War of the Ring. He opposed Sauron, and, other than having studied him, had no connection to him whatsoever. He was power hungry and served no one but himself. He had aspirations of eventually ruling all of Middle Earth.
In the films, Saruman was portrayed as being nothing but a servant of Sauron, and a much weaker character in terms of ambition. I don't know why Jackson & company chose to portray him that way, but my guess is that they wanted to streamline the war into having two distinct sides, and make it easier for the audience to just see "good vs evil".
It's also been suggested that they used Saruman in the films as a "substitue" antagonist for Sauron, since the latter is never seen onscreen, and that Christopher Lee's popularity contributed to that.
Regardless of how you choose to look at it, the character in the films was *much* different than the one in the books.