donkey engine vs switch engine

donkey engine and switch engine both are nouns.

Word	Noun	Adjective	Verb	Adverb
donkey engine	Yes	No	No	No
switch engine	Yes	No	No	No

As nouns, donkey engine and switch engine are synonyms defined as:

donkey engine and switch engine: a locomotive for switching rolling stock in a railroad yard

donkey engine (noun)	switch engine (noun)
(nautical) a small engine (as one used on board ships to operate a windlass)	a locomotive for switching rolling stock in a railroad yard
a locomotive for switching rolling stock in a railroad yard