common bile duct vs bile duct

common bile duct and bile duct both are nouns.

Word	Noun	Adjective	Verb	Adverb
common bile duct	Yes	No	No	No
bile duct	Yes	No	No	No

As nouns, common bile duct and bile duct are synonyms defined as:

common bile duct and bile duct: a duct formed by the hepatic and cystic ducts; opens into the duodenum

common bile duct (noun)	bile duct (noun)
a duct formed by the hepatic and cystic ducts; opens into the duodenum	a duct formed by the hepatic and cystic ducts; opens into the duodenum