The Shining as a film legits butchers the entire bluntness of the book in favor of some shit about being "ambiguous". In the book it was EXTREMELY obvious, that everything going on was paranormal, and it got pretty trippy as well with the scares, whereas the movie doesn't even give a convincing Jack.
The scene with the dead lady in room
217 237 is scarier than anything in King's book.
But more to the point, there is
moral ambiguity in the book that Kubrick scrapped. Book Jack is clearly somebody we're supposed to sympathize with: a guy with talent and promise who ultimately succumbs to his own demons. He's clearly a semi-autobiographical figure, with the rampant drinking and being a teacher to make ends meet until his writing career takes off (which it never does -- maybe it was King asking himself what might have been if his own writing had flamed out before he achieved success). The hotel feeds his inner turmoil and ultimately turns him into a monster, with him grasping a thread of redemption in giving Danny a chance to run before the Overlook consumes him completely.
Kubrick took one look at this character and decided, "Nope, he's a piece of shit, and he's going to be a piece of shit from the jump." I have no idea if it's the case, but I wonder if it was the fact that Jack once broke Danny's arm that sealed that particular deal. It's not that Jack goes crazy too quickly, as is often claimed, but that he's just a wretched human being from the moment we meet him.
The other big difference is that Movie Jack
clearly loathes his wife and can't wait to be shut of her. Shelly Duvall plays Wendy much more as an abused spouse than the way the character is written in the book -- compare the scene in the doctor's office where she recounts how Danny's arm was broken. In the movie it feels far more like a beaten woman telling the same bad lies she's had to tell for years to cover up for her asshole spouse.
I think they're both quite excellent stories, each doing something different with the same material, but the older I get the more I lean toward what we see in Kubrick's film.