demonstrator vs teacher

demonstrator and teacher both are nouns.

Word	Noun	Adjective	Verb	Adverb
demonstrator	Yes	No	No	No
teacher	Yes	No	No	No

As nouns, teacher is a hypernym of demonstrator; that is, teacher is a word with a broader meaning than demonstrator:

demonstrator: a teacher or teacher's assistant who demonstrates the principles that are being taught
teacher: a person whose occupation is teaching

Other hypernyms of demonstrator include instructor.

demonstrator (noun)	teacher (noun)
someone who participates in a public display of group feeling	a personified abstraction that teaches
someone who demonstrates an article to a prospective buyer	a person whose occupation is teaching
a teacher or teacher's assistant who demonstrates the principles that are being taught