brown bread vs whole wheat bread

brown bread and whole wheat bread both are nouns.

Word	Noun	Adjective	Verb	Adverb
brown bread	Yes	No	No	No
whole wheat bread	Yes	No	No	No

As nouns, brown bread and whole wheat bread are synonyms defined as:

Other synonyms of brown bread include dark bread, whole meal bread.

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