Honestly, I think the only thing you need to know to understand how the books and the movies differ is that, in the books, the ring is destroyed half-way through the last book...
I prefer the ending in the film, that the go back to the shire as ordinary folk. That when Sam proposes to his sweetheart he does it not as a conquering hero, but as a humble, nervous young man. "It was the bravest thing he ever did". Perfect.
I don't know... I always thought that Saruman as a cheap hood was the weakest part of the book, and it doesn't really work unless you also take the time in Fellowship to go into the whole Bill Ferny thing, which would lead to Maggot as more than a mention. At some point you have to make the story fit the screen, and I think Jackson did that admirably. Even keeping the Men of the Mountains going until the end of the Battle of Pelennor fields made sense, in that it didn't have to involve the Rangers and another whole army raised elsewhere. It wasn't the original story, but it was an elegant solution to a story-telling problem.
I much prefer the movie approach where The Shire and its inhabitants remain largely oblivious to and untouched by all the evil, death and suffering that has happened. It's almost as if everything happened so a little part of the world could remain innocent like a child.
Well, this was a major theme in the book - how you can never go back to innocence and pretend all the bad stuff didn't happen. But in Hollywood everything is happily-ever-after and we never have to learn from our mistakes.
