sour bread vs staff of life

sour bread and staff of life both are nouns.

Word	Noun	Adjective	Verb	Adverb
sour bread	Yes	No	No	No
staff of life	Yes	No	No	No

As nouns, staff of life is a hypernym of sour bread; that is, staff of life is a word with a broader meaning than sour bread:

sour bread: made with a starter of a small amount of dough in which fermentation is active
staff of life: food made from dough of flour or meal and usually raised with yeast or baking powder and then baked

Other hypernyms of sour bread include bread, breadstuff.

sour bread (noun)	staff of life (noun)
made with a starter of a small amount of dough in which fermentation is active	food made from dough of flour or meal and usually raised with yeast or baking powder and then baked