OK, the 1918 film Tarzan of the Apes (see preceding post) differed from the book in a bunch of ways.
Tarzan didn't have to wait for a sequel to get the girl. He didn't have to learn French.
The movie spares us the ape conversations. Who wants to know that tarzan is ape for white skin?
No ape language means less ape politics. Who needs to know KA-GODA is ape for "Do you surrender?"
It was only 6 years from the time Edgar Rice Burrough's novel was first printed in serial form to the time the movie came out, but it was a very momentous 6 years that included WW I, so it isn't surprising that there is a huge change right at the beginning in the fundamental setup.
The book says John Clayton, Lord Greystoke, was commissioned to go to Africa to investigate charges that another European power is recruiting natives as soldiers to raid and plunder the black subjects of a West African Coast British Colony. In other words, the fundamental context is that of colonials against colonials. The Europeans are fighting for control of Africa, colonialism is a neutral fact of life, The Good Guys are the ones who use guns as a last resort instead of right off the bat. The Bad Guys commit the racial crime of betrayal (of the White Race): arming Black natives.
In the movie, the villains are Arab slave traders. The Arabs are mainly dealing in Black slaves, but a new White character, the defender Binns, is introduced, to put a sympathetic White face on the victims of bad "Arab" slavery. The context is White colonialists to the rescue, saving mostly a weak non-white race, but also a few of their own, from enslavement by a less weak non-white race.
In the book Alice Rutherford-Clayton comes along simply to be by her man's side during what may be a long assignment. In the movie we see Lady Alice anxious to go and getting all feminist up in the suggestion that she stay behind. "Is courage only for men, then?"
In fact throughout the movie, even later with Jane being carried around and protected by Tarzan like a favorite rag doll, there is a constant effort to show the women as being at least as courageous as the men, and not being, in principle, chattel. In contrast to the way the natives are generally depicted.
One way the film exactly matches the book is in the romanticized Darwinianism. I've always been amazed by the silly White fantasy that imagines that White people came from the jungle just like Blacks, but, being White and so having a natural Darwinian advantage, triumphed over the jungle and escaped its clutches, leaving the inferior others behind as they clawed their way to Bonn, London, Oslo, and Peoria.
Edgar R put it like this (John speaking to Alice as they begin life stranded in the jungle): "Hundreds of thousands of years ago our ancestors of the dim and distant past faced the same problems which we must face, possibly in these same primeval forests. That we are here today evidences their victory."
[I suppose any Tarzan movie made today that addressed the origins of White People would have to allow leeway for the Creationist view.]
There being no Mr. Binns, the book Tarzan has to perform the improbable task of learning to read and write from looking at the books alone. That's reason enough to introduce him, in my opinion, without all the slave trade business.
The silliness about Tarzan's "little English heart" and "little English head" is in the book! "At the bottom of his little English heart beat the great desire to cover his nakedness with CLOTHES for he had learned from his picture books that all MEN were so covered, while MONKEYS and APES and every other living thing went naked." Funny.
Tarzan's killing of the native who killed Kala was an occasion in the book for Tarzan to learn about fire for the first time, and also for Edgar R to insert this bit of genetic fantasy: "Did men eat men? Alas, he did not know. Why, then, this hesitancy! Once more he essayed the effort, but a qualm of nausea overwhelmed him. He did not understand... All he knew was that he could not eat the flesh of this black man, and thus hereditary instinct, ages old, usurped the functions of his untaught mind and saved him from transgressing a worldwide law of whose very existence he was ignorant."
The movie doesn't show Tarzan committing gratuitous acts of violence. In the book, Tarzan doesn't steal clothes from the natives until the onset of puberty, and when he does, he gets it off a native he kills for that sole purpose. It's not a kid's prank. He really wants those clothes. It's like, "Let me borrow that top, Betch."
The movie and the book agree on the contents of the note Tarzan places on the door of the cabin. For the book, however, it represents an inconsistency, since supposedly book Tarzan doesn't know the phonetic values of letters, so he can only read the meanings of words and not sound them out. So how does he know how to spell "Tarzan?"