inhalation vs medicinal drug

inhalation and medicinal drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
inhalation	Yes	No	No	No
medicinal drug	Yes	No	No	No

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

inhalation: a medication to be taken by inhaling it
medicinal drug: (medicine) something that treats or prevents or alleviates the symptoms of disease

Other hypernyms of inhalation include medicament, medication, medicine.

inhalation (noun)	medicinal drug (noun)
the act of inhaling; the drawing in of air (or other gases) as in breathing	(medicine) something that treats or prevents or alleviates the symptoms of disease
a medication to be taken by inhaling it