epicyclic gear train vs gearing

epicyclic gear train and gearing both are nouns.

Word	Noun	Adjective	Verb	Adverb
epicyclic gear train	Yes	No	No	No
gearing	Yes	No	No	No

As nouns, gearing is a hypernym of epicyclic gear train; that is, gearing is a word with a broader meaning than epicyclic gear train:

epicyclic gear train: a system of epicyclic gears in which at least one wheel axis itself revolves about another fixed axis
gearing: wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed

Other hypernyms of epicyclic gear train include gear, geartrain, power train, train.

epicyclic gear train (noun)	gearing (noun)
a system of epicyclic gears in which at least one wheel axis itself revolves about another fixed axis	wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed