demonstrator vs demonstrate

demonstrator is a noun but demonstrate is not a noun.

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

demonstrator (noun)	demonstrate (noun)
someone who participates in a public display of group feeling
someone who demonstrates an article to a prospective buyer
a teacher or teacher's assistant who demonstrates the principles that are being taught

demonstrator (verb)	demonstrate (verb)
	establish the validity of something, as by an example, explanation or experiment
	provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
	give an exhibition of to an interested audience
	march in protest; take part in a demonstration