yeast vs yeast cake

yeast and yeast cake both are nouns.

Word	Noun	Adjective	Verb	Adverb
yeast	Yes	No	No	No
yeast cake	Yes	No	No	No

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

yeast: a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey
yeast cake: small cake of compressed moist yeast

Other hyponyms of yeast include brewer's yeast, mother.

yeast (noun)	yeast cake (noun)
any of various single-celled fungi that reproduce asexually by budding or division	small cake of compressed moist yeast
a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey