Imaginación vs. fantasía

'Imaginación' and 'fantasía' are two Spanish words that both connect to the concept of 'imagination', the power of the mind to conceive or form mental images, ideas or concepts that are not actually present. These words, while having similarities, also have differences in their specific usage in the Spanish language.

Imaginación

This word refers to the ability to form new concepts in the mind that are not directly available from the senses. It's usually used to describe ideas related to inventiveness, creativity and original thought.
Él tiene una imaginación increíble para crear historias.
(He has an incredible imagination for creating stories.)
Usa tu imaginación para resolver este problema.
(Use your imagination to solve this problem.)

Fantasía

Fantasía usually refers more to a world of illusion or unreality - things imagined rather than things invented. It typically deals with imaginative conception freed from reality; it's primarily associated with a dream world, or fictitious creations.
Ella disfruta viviendo en su mundo de fantasía.
(She enjoys living in her fantasy world.)
La novela está llena de criaturas de fantasía.
(The novel is full of fantasy creatures.)

Summary

'Imaginación' and 'fantasía' both deal with the act of forming ideas in our minds, but they diverge when it comes to the realism of these ideas. While 'imaginación' embraces inventiveness and creativity that may lead to applicable solutions or new thoughts, 'fantasía' leans towards a world of dreams, illusions and unreal scenarios.