epicyclic gear vs planet gear

epicyclic gear and planet gear both are nouns.

Word	Noun	Adjective	Verb	Adverb
epicyclic gear	Yes	No	No	No
planet gear	Yes	No	No	No

As nouns, epicyclic gear and planet gear are synonyms defined as:

epicyclic gear and planet gear: an outer gear that revolves about a central sun gear of an epicyclic train

Other synonyms of epicyclic gear include planet wheel, planetary gear.

epicyclic gear (noun)	planet gear (noun)
an outer gear that revolves about a central sun gear of an epicyclic train	an outer gear that revolves about a central sun gear of an epicyclic train