Horror typically relies on the shock or dread of the unknown, often manifesting as an external monster, a supernatural force, or a physical predator. The objective is frequently to elicit a visceral reaction—such as disgust, terror, or panic—rooted in the threat of physical harm or the violation of natural laws.
In contrast, the psychological thriller shifts the focus inward. While the antagonist may be a person, the true conflict resides in the mental state of the characters. These stories leverage suspense, paranoia, and the manipulation of perception to create an atmosphere of instability, where the threat is often hidden within the character's own psyche or a trusted relationship.