epicyclic train vs geartrain

epicyclic train and geartrain both are nouns.

Word	Noun	Adjective	Verb	Adverb
epicyclic train	Yes	No	No	No
geartrain	Yes	No	No	No

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

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

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

epicyclic train (noun)	geartrain (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