barycenter vs centre of mass

barycenter and centre of mass both are nouns.

Word	Noun	Adjective	Verb	Adverb
barycenter	Yes	No	No	No
centre of mass	Yes	No	No	No

As nouns, centre of mass is a hypernym of barycenter; that is, centre of mass is a word with a broader meaning than barycenter:

barycenter: (astronomy) the common center of mass around which two or more bodies revolve
centre of mass: point representing the mean position of the matter in a body

Other hypernyms of barycenter include center of mass.

barycenter (noun)	centre of mass (noun)
(astronomy) the common center of mass around which two or more bodies revolve	point representing the mean position of the matter in a body