diphenylhydantoin vs hydantoin

diphenylhydantoin and hydantoin both are nouns.

Word	Noun	Adjective	Verb	Adverb
diphenylhydantoin	Yes	No	No	No
hydantoin	Yes	No	No	No

As nouns, hydantoin is a hypernym of diphenylhydantoin; that is, hydantoin is a word with a broader meaning than diphenylhydantoin:

diphenylhydantoin: an anticonvulsant drug (trade name Dilantin) used to treat epilepsy and that is not a sedative
hydantoin: any of a group of anticonvulsant drugs used in treating epilepsy

diphenylhydantoin (noun)	hydantoin (noun)
an anticonvulsant drug (trade name Dilantin) used to treat epilepsy and that is not a sedative	any of a group of anticonvulsant drugs used in treating epilepsy