cotton cake vs cottonseed cake

cotton cake and cottonseed cake both are nouns.

Word	Noun	Adjective	Verb	Adverb
cotton cake	Yes	No	No	No
cottonseed cake	Yes	No	No	No

As nouns, cotton cake and cottonseed cake are synonyms defined as:

cotton cake and cottonseed cake: the solid matter remaining after oil has been pressed from cottonseeds

cotton cake (noun)	cottonseed cake (noun)
the solid matter remaining after oil has been pressed from cottonseeds	the solid matter remaining after oil has been pressed from cottonseeds