stage monitor vs speaker unit

stage monitor and speaker unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
stage monitor	Yes	No	No	No
speaker unit	Yes	No	No	No

As nouns, speaker unit is a hypernym of stage monitor; that is, speaker unit is a word with a broader meaning than stage monitor:

stage monitor: One of the speakers on stage pointing towards the performers to help them hear themselves.
speaker unit: electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance

Other hypernyms of stage monitor include loudspeaker, loudspeaker system, speaker, speaker system.

stage monitor (noun)	speaker unit (noun)
One of the speakers on stage pointing towards the performers to help them hear themselves.	electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance