Sueño vs. ensueño
The Spanish language has multiple words that can be used to express the concept of 'dream', primarily 'sueño' and 'ensueño'. Although they share the same root, there are subtle differences in meaning and usage between these terms.
Sueño
The term 'sueño' might be used to refer to both the physiological process of dreaming during sleep and the figurative sense of personal goals or aspirations.
Tengo un sueño muy extraño anoche.
(I had a very strange dream last night.)
Mi mayor sueño es viajar por todo el mundo.
(My biggest dream is to travel around the world.)
Ensueño
'Ensueño' is a more poetic or literary term that refers to a dream-like state, an illusion, or a daydream. It can also denote something unreal or fantastic that exists only in the imagination.
Fue como un ensueño vivir en París durante un año.
(Living in Paris for a year was like a dream.)
Se perdió en un ensueño mientras miraba el océano.
(She lost herself in a daydream as she stared at the ocean.)
Summary
'Sueño' and 'ensueño' are both Spanish words related to dreams. However, 'sueño' is more commonly used to describe dreams we have when sleeping and our ambitions, while 'ensueño' has a more poetic connotation, portraying dream-like states, illusions, and daydreams.