Illusion, from a psychological perspective, is a mistaken sensory response, such as seeing an apple as an orange, or hearing someone talking when there is no sound.
When experiencing illusions, people often find it difficult to discern whether it is indeed an illusion, because it stems from one's own senses.
An illusion realm is different from a simple illusion; it is not a sensory misjudgment but rather something nonexistent that directly appears in one's consciousness, somewhat like dreaming.
The difference between an illusion realm and a dream is that the person is awake and knows they are awake. It is usually very clear, complete, and coherent, even unfolding with changes that follow its internal logic.
Cultivators can typically discern the illusion realm, knowing clearly that everything they see does not exist in reality.
