If by different you mean that Tarzan and Jane move back to England, get married, do pretty well for themselves and then move back to Africa, then yeah, the books are very different from the moves. Also, Tarzan is really smart and can speak several different human languages and weird stuff happens, like Tarzan and the rest of his family become immortal weird...
Keep in mind that the original Tarzan novels were written by Edgar Rice Burroughs, who is also well known for his John Carter of Mars series and The Land That Time Forgot series. So several Sci-Fi elements creep into the later novels like finding lost civilizations, visiting other planets, ect.
Fortunetly, the first eight books in the series are out of copyright now in the USA and can be found on
http://www.gutenberg.org ...