leavening vs sourdough

leavening and sourdough both are nouns.

Word	Noun	Adjective	Verb	Adverb
leavening	Yes	No	No	No
sourdough	Yes	No	No	No

As nouns, sourdough is a hyponym of leavening; that is, sourdough is a word with a more specific, narrower meaning than leavening:

leavening: a substance used to produce fermentation in dough or a liquid
sourdough: a leaven of dough in which fermentation is active; used by pioneers for making bread

Other hyponyms of leavening include baking powder, barm, yeast.

leavening (noun)	sourdough (noun)
an influence that works subtly to lighten or modify something	a settler or prospector (especially in western United States or northwest Canada and Alaska)
a substance used to produce fermentation in dough or a liquid	a leaven of dough in which fermentation is active; used by pioneers for making bread