mephobarbital vs barbiturate

mephobarbital and barbiturate both are nouns.

Word	Noun	Adjective	Verb	Adverb
mephobarbital	Yes	No	No	No
barbiturate	Yes	No	No	No

As nouns, barbiturate is a hypernym of mephobarbital; that is, barbiturate is a word with a broader meaning than mephobarbital:

mephobarbital: a long-acting crystalline barbiturate (trade name Mebaral) used as a sedative and as an anticonvulsant in the treatment of epilepsy
barbiturate: organic compound having powerful soporific effect; overdose can be fatal

Other hypernyms of mephobarbital include anticonvulsant, anticonvulsant drug, antiepileptic, antiepileptic drug.

mephobarbital (noun)	barbiturate (noun)
a long-acting crystalline barbiturate (trade name Mebaral) used as a sedative and as an anticonvulsant in the treatment of epilepsy	organic compound having powerful soporific effect; overdose can be fatal