sleeping pill vs hypnotic

sleeping pill and hypnotic both are nouns.

Word	Noun	Adjective	Verb	Adverb
sleeping pill	Yes	No	No	No
hypnotic	Yes	Yes	No	No

As nouns, hypnotic is a hypernym of sleeping pill; that is, hypnotic is a word with a broader meaning than sleeping pill:

sleeping pill: a soporific drug in the form of a pill (or tablet or capsule)
hypnotic: a drug that induces sleep

Other hypernyms of sleeping pill include lozenge, pill, tab, tablet, soporific.

sleeping pill (noun)	hypnotic (noun)
a soporific drug in the form of a pill (or tablet or capsule)	a drug that induces sleep

sleeping pill (adjective)	hypnotic (adjective)
	of or relating to hypnosis
	attracting and holding interest as if by a spell