cottonseed cake vs cotton cake

cottonseed cake and cotton cake both are nouns.

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

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

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

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