Ritalin vs stimulant drug

Ritalin and stimulant drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ritalin	Yes	No	No	No
stimulant drug	Yes	No	No	No

As nouns, stimulant drug is a hypernym of Ritalin; that is, stimulant drug is a word with a broader meaning than Ritalin:

Ritalin: central nervous system stimulant (trade name Ritalin) used in the treatment of narcolepsy in adults and attention deficit disorder in children
stimulant drug: a drug that temporarily quickens some vital process

Other hypernyms of Ritalin include excitant, stimulant.

Ritalin (noun)	stimulant drug (noun)
central nervous system stimulant (trade name Ritalin) used in the treatment of narcolepsy in adults and attention deficit disorder in children	a drug that temporarily quickens some vital process