brown bread vs Boston brown bread

brown bread and Boston brown bread both are nouns.

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

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

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

brown bread (noun)	Boston 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