branched chain vs open chain

branched chain and open chain both are nouns.

Word	Noun	Adjective	Verb	Adverb
branched chain	Yes	No	No	No
open chain	Yes	No	No	No

As nouns, open chain is a hypernym of branched chain; that is, open chain is a word with a broader meaning than branched chain:

branched chain: an open chain of atoms with one or more side chains attached to it
open chain: a chain of atoms in a molecule whose ends are not joined to form a ring

branched chain (noun)	open chain (noun)
an open chain of atoms with one or more side chains attached to it	a chain of atoms in a molecule whose ends are not joined to form a ring