white bread vs light bread

white bread and light bread both are nouns.

Word	Noun	Adjective	Verb	Adverb
white bread	Yes	No	No	No
light bread	Yes	No	No	No

As nouns, white bread and light bread are synonyms defined as:

white bread and light bread: bread made with finely ground and usually bleached wheat flour

white bread (noun)	light bread (noun)
bread made with finely ground and usually bleached wheat flour	bread made with finely ground and usually bleached wheat flour