dumbwaiter vs food elevator

dumbwaiter and food elevator both are nouns.

Word	Noun	Adjective	Verb	Adverb
dumbwaiter	Yes	No	No	No
food elevator	Yes	No	No	No

As nouns, dumbwaiter and food elevator are synonyms defined as:

dumbwaiter and food elevator: a small elevator used to convey food (or other goods) from one floor of a building to another

dumbwaiter (noun)	food elevator (noun)
a small elevator used to convey food (or other goods) from one floor of a building to another	a small elevator used to convey food (or other goods) from one floor of a building to another