narcotic vs soporiferous

narcotic is a noun but soporiferous is not a noun.

Word	Noun	Adjective	Verb	Adverb
narcotic	Yes	Yes	No	No
soporiferous	No	Yes	No	No

As adjectives, narcotic and soporiferous are synonyms defined as:

Other synonyms of narcotic include soporific.

narcotic (noun)	soporiferous (noun)
a drug that produces numbness or stupor; often taken for pleasure or to reduce pain; extensive use can lead to addiction

narcotic (adjective)	soporiferous (adjective)
of or relating to or designating narcotics	sleep inducing
inducing stupor or narcosis	inducing mental lethargy
inducing mental lethargy