Horror

To truly answer this question would take more time than anyone should bother with, but I can give the overall differences:

• Missing from the movie was the character of Patrick Hockstetter, as well as a few more minor characters, and the history of the monster in the town of Derry. In the movie, Beverly didn't have sex with the boys in the tunnels on their way out after they believed they killed the monster when they were 12 (early).
• The character of Beverly Marsh in the book was a very tough tomboyish girl who didn't take crap from anyone (except her father). In the movie, she was played by actresses who portrayed her as very meek, both in her 12 year old and adult years.
• The movie left out the entire part of the book when they were in the "macrospace" and mentally fighting the monster. In the movie this was simply portrayed as them being hypnotized by the monster.
• In the movie, the 12 year old group never made it to the "lair of it". They met up with Pennywise in the cellars in some random place.
• No mention of the Turtle in the movie.
• Many interactions with Henry were left out of the movie.

There are so many more differences, but I think I hit on most of the ones that really took away important context from the movie version.

Well, horror is scary, like with killing and demons and stuff. Gothic is more like witchcraft.

ANSWER:

Gothic tales depend primarily on Atmosphere for their effect on the reader: such devices as creaky staircases, damp dungeons, and gloomy mansions are used, sometimes with elements of the Occult, to produce a sense of inescapable Gloom and Doom which threatens the Heroine with unmentioned terrors. There is never - or extremely seldom - any actual blood and gore to be found. The plot of such stories almost always involves the heroine meeting a Dark and Forbidding Lord, who winds up rescuing her from the Menace - or, whom She rescues. For their time, these novels were remarkable for the equality of the protagonists; the heroines are always strong, capable women. Jane Eyre is one example of the Genre, as is Northanger Abbey. These stories were Extremely popular during the late 18th Century and the Victorian Era, particularly with women, but have generally enjoyed great popularity since the invention of the Novel. Many elements of the Gothic Genre have been blended into the Romantic Novels of today.

Horror, on the other hand, is usually much less subtle in its efforts to raise the hair of the reader or viewer. Monsters, Vampires and the Undead, combined with buckets of blood and gore, are the usual tools employed. Sometimes, the Horror Genre brings out the "Monsters Under The Bed" of small towns, as in "The Lottery"; sometimes it gleefully rampages through a bevy of College students. Sometimes it can be Socially Valuable, as with Frankenstein, in which the Monster is actually the Victim of intolerance. In Some Horror the Monsters are just plain folks. Think of Misery.

In the Horror Genre the Terrors are Real. In Gothic they're Atmospheric.

You generally find Count Dracula is introduced in movies when he first opens the door to Jonathan Harker at Castle Dracula. It is always a dramatic way to initiate the appearance of such a sinister character. This has happened right from the beginning when the silent film Nosferatu was made. Right through to Bela Lugosi standing on top of the steps, and Gary Oldman and his sweeping gestures inviting Harker in:

"Count Dracula?" He bowed in a courtly way as he replied:-

"I am Dracula. And I bid you welcome, Mr. Harker, to my house. Come in; the night air is chill, and you must need to eat and rest."

She is borderline psychotic (progressing steadily into full-on psychosis as the novel/movie progresses). Even just 1/4 of the way through, the writer character (Paul Sheldon) has already voiced his concern (to the reader, of course) that Annie Wilkes is borderline psychotic:

"Because of his researches for Misery, he had rather more than a layman's understanding of neurosis and psychosis, and he knew that although a borderline psychotic might have alternating periods of deep depression and almost aggressive cheerfulness and hilarity, the puffed and infected ego underlay all, positive that all eyes were upon him or her, positive that he or she was starring in a great drama; the outcome was a thing for which untold millions waited with held breath.

Such an ego simply forbade certain lines of thought. These lines were predictable because they all stretched in the same direction: from the unstable person to objects, situations, or other persons outside of the subject's field of control (or fantasy: to the neurotic there might be some difference but to the psychotic they were one and the same).

Annie Wilkes had wanted Fast Cars destroyed, and so, to her, there had only been the one copy," (Viking Penguin hardcover edition, p50).