engine vs donkey engine

engine and donkey engine both are nouns.

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

As nouns, donkey engine is a hyponym of engine; that is, donkey engine is a word with a more specific, narrower meaning than engine:

engine: motor that converts thermal energy to mechanical work
donkey engine: (nautical) a small engine (as one used on board ships to operate a windlass)

As nouns, donkey engine is a hyponym of engine; that is, donkey engine is a word with a more specific, narrower meaning than engine:

engine: a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks
donkey engine: a locomotive for switching rolling stock in a railroad yard

engine (noun)	donkey engine (noun)
motor that converts thermal energy to mechanical work	(nautical) a small engine (as one used on board ships to operate a windlass)
a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks	a locomotive for switching rolling stock in a railroad yard
an instrument or machine that is used in warfare, such as a battering ram, catapult, artillery piece, etc.
something used to achieve a purpose