branch vs brachium

branch and brachium both are nouns.

Word	Noun	Adjective	Verb	Adverb
branch	Yes	No	Yes	No
brachium	Yes	No	No	No

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

Other hyponyms of branch include bifurcation, crotch, fork.

branch (noun)	brachium (noun)
any projection that is thought to resemble a human arm	(biology) a branching or armlike part of an animal
a division of some larger or more complex organization
a stream or river connected to a larger one
a natural consequence of development
a division of a stem, or secondary stem arising from the main stem of a plant
a part of a forked or branching shape

branch (verb)	brachium (verb)
divide into two or more branches so as to form a fork
grow and send out branches or branch-like structures