Hi,
This is what Wikipedia has to say about
horror (film):
In film, the horror genre is characterized by the attempt to make the viewer experience fright, fear, terror, disgust or horror. Its plots often involve the intrusion of an evil force, event, or personage, sometimes of supernatural origin, into the mundane world.
Some of the most common elements include vampires, zombies (and other forms of resurrected corpses), werewolves, ancient curses, ghosts, demons and/or demonic possession, Satanism, evil children, 'slasher villains', vicious animals, inanimate objects brought to life by black magic or twisted science, haunted houses, cannibals, and malicious extraterrestrials. The serial killer movie is sometimes regarded as part of the horror genre.
Specific stories and characters, often derived from classic literature, have also proven popular, and have inspired many sequels, remakes, and copycats. These include Dracula, Frankenstein, The Mummy, The Wolf Man, The Phantom of the Opera and Dr. Jekyll and Mr. Hyde.
The horror film is often associated with low budgets and exploitation, but major studios and well-respected directors
have made intermittent forays into the genre. The genre's marginal
status has caused it to receive much critical dismissal or moral
condemnation over the course of film history. However, during the past
few decades new generations of critics - more inclined to take popular
genres seriously - have given horror substantial attention and
analysis, especially with regard to its perceived subversive content.
Over the same period, it has become more than ever a source of
controversy, as its level of graphic violence has increased and
accusations of misogyny have been leveled, especially by feminist critics.
Some horror films owe a substantial amount to other genres, particularly science fiction, fantasy, dark comedy and thriller. The lines between horror and these other categories are often a subject of debate among fans and critics.
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And here's
thriller:
The thriller is a broad genre of literature, film, and television
that includes numerous, often-overlapping sub-genres. Thrillers are
typically characterized by fast pacing, frequent action scenes, and
plots in which a small number of resourceful heroes must thwart, often violently, the plans of more-powerful and better-equipped villains. Thrillers typically emphasize plot over character development, and make extensive use of literary devices such as suspense, red herrings, and cliffhangers.
They often take place wholly or partly in exotic settings such as
foreign cities, deserts, the polar regions, or the high seas. The
heroes of modern thrillers are often "hard men" accustomed to danger:
law enforcement officers, spies, soldiers, seamen, divers, or pilots.
The heroes of earlier thrillers (especially those written before the
1980s) are more likely to be ordinary citizens drawn into dangerous
circumstances by accident. They are almost inevitably men, though women
are increasingly common as secondary characters.
Thrillers overlap with mystery stories, but are distinguised from
mainstream mysteries by the structure of their plots. The thriller hero
typically tries to thwart the plans of an enemy whose identity he
already knows, rather than discover (after the fact) who is behind a
crime already committed. The thriller villains typically plan crimes on
the grand scale: serial or mass murder, terrorism, assassination, or
the overthrow of governments. Violent confrontations between the hero
and the villain, though not uncommon in mystery stories, are standard
in thrillers. Similar distinctions separate the thriller genre from
others with which it overlaps: adventure, spy, legal, war, and maritime
fiction, for example.
Thrillers are, ultimately, defined not by their subject matter but
by their approach to it. Many thrillers (for example) involve spies and
the business of espionage, but not all spy stories are thrillers. The
spy novels of John LeCarre,
for example, explicitly and intentionally rejected the conventions of
the thriller. Many thriller writers have written novels in related
genres that have few or no thriller elements. Alistair MacLean, Hammond Innes, and Brian Callison,
for example, are best known for their thrillers but are also
accomplished writers of straightforward man-against-nature sea stories.