In the original Edgar Rice Burroughs novel, Tarzan was adopted by apes and the only gorilla mentioned was Bolgani the Great, who was an enemy of Tarzan and the troop. This is the first Tarzan movie were the apes that adopt him are gorillas instead of chimpanzees.
Tantor was an old bull elephant disliked by the denizens of the jungle, Sabor was a lioness, and Terkoz (presumably “Terkina” known as “Terk”) was a male ape and Tarzan’s arch-nemesis within the troop.
Kerchak murdered Tarzan’s family. The producers changed it not only to make him more sympathetic, but also to make it less gruesome for families.
Even though Clayton (first name William in the book) is a villain in the movie, he and Tarzan are actually cousins according to the original story from Burroughs. William being after Tarzan in line of succession and therefore wouldn’t want him to be alive.
In the film, Jane Porter and her father are from London. In the novel, they are American citizens.