death cap vs death cup

death cap and death cup both are nouns.

Word	Noun	Adjective	Verb	Adverb
death cap	Yes	No	No	No
death cup	Yes	No	No	No

As nouns, death cap and death cup are synonyms defined as:

death cap and death cup: extremely poisonous usually white fungus with a prominent cup-shaped base; differs from edible Agaricus only in its white gills

Other synonyms of death cap include Amanita phalloides, death angel, destroying angel.

death cap (noun)	death cup (noun)
extremely poisonous usually white fungus with a prominent cup-shaped base; differs from edible Agaricus only in its white gills	extremely poisonous usually white fungus with a prominent cup-shaped base; differs from edible Agaricus only in its white gills