Horror and terror are two feelings that scared people experience. When a person is afraid, it might be because of horror or terror.
Horror is when something happens that is so scary that it gives a person a feeling of disgust or revulsion. It makes them feel sick in their stomach or maybe even want to throw up. Imagine seeing a monster or a ghost or a person with gross and scary injuries. That kind of thing might give someone a feeling of horror.
Terror, on the other hand, is when a person feels very scared and full of fear because of something that they think might happen to them. It's the feeling of being scared that they can't escape or run away from, like being trapped in a haunted house or in a dark forest.
In summary, horror is when something scary happens that makes you feel sick or disgusted, and terror is when you feel really scared and like you can't escape from what's happening.