Fantasy Illusion in Chinese / Japanese...

幻想 is illusions or fantasy in Chinese, Japanese Kanji, and old Korean Hanja.

This can also refer to delusion or daydreaming. It sort of means a dream or idea that cannot be true or real ( at least not in this realm).

鏡花水月 is an old Asian proverb that means “flowers in a mirror and the moon reflected in the lake” or “flowers reflected on a mirror and the moon reflected on the water's surface.”

Literally, 鏡花水月 reads “Mirror Flower, Water Moon.”

Figuratively this can be used to represent a lot of different ideas. It can be used to express an unrealistic rosy view or viewing things through rose-tinted spectacles. So you can use it to relay an idea about something that is visible but has no substance, something that can be seen but not touched, or something beautiful but unattainable such as dreams or a mirage.

This expression is used to describe things like the subtle and profound beauty of poems that cannot be described in words.

鏡 = Mirror (or lens)
花 = Flower(s)
水 = Water
月 = Moon

Can also be written 水月鏡花 (just a slight change in word/character order).

幻像 is a universal word for Illusion in Chinese, Japanese Kanji, and old Korean Hanja.

The first character means phantasm, vision, dream, illusion, apparition, or fantasy.

The second character means statue, picture, image, figure, portrait, shape, form, appearance, to be like, to resemble, to take after, to seem, or in rare/ancient context: an elephant.

Note that the first character can be written without the left-side radical in Chinese. This form is shown to the right. Both forms are acceptable in Chinese but the character shown to the right is more likely to be read as "elephant."

See Also:  Reality

真妄 is a specifically Buddhist term that means “reality and illusion.” Out of Buddhist context, it might be read as “The real and the absurd.”

Separately, the first character means real, true, and genuine, and the second character means absurd, fantastic, or related to fantasy.