Boston brown bread vs brown bread

Boston brown bread and brown bread both are nouns.

Word	Noun	Adjective	Verb	Adverb
Boston brown bread	Yes	No	No	No
brown bread	Yes	No	No	No

As nouns, Boston brown bread and brown bread are synonyms defined as:

Boston brown bread and brown bread: dark steamed bread made of cornmeal wheat and flour with molasses and soda and milk or water

Boston brown bread (noun)	brown bread (noun)
dark steamed bread made of cornmeal wheat and flour with molasses and soda and milk or water	dark steamed bread made of cornmeal wheat and flour with molasses and soda and milk or water
	bread made with whole wheat flour