dream vs imagery

dream and imagery both are nouns.

Word	Noun	Adjective	Verb	Adverb
dream	Yes	No	Yes	No
imagery	Yes	No	No	No

As nouns, imagery is a hypernym of dream; that is, imagery is a word with a broader meaning than dream:

Other hypernyms of dream include imagination, imaging, mental imagery.

dream (noun)	imagery (noun)
a series of mental images and emotions occurring during sleep	the ability to form mental images of things or events
imaginative thoughts indulged in while awake
a fantastic but vain hope (from fantasies induced by the opium pipe)
a state of mind characterized by abstraction and release from reality
a cherished desire
someone or something wonderful

dream (verb)	imagery (verb)
have a daydream; indulge in a fantasy
experience while sleeping