sleeping pill vs lozenge

sleeping pill and lozenge both are nouns.

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

As nouns, lozenge is a hypernym of sleeping pill; that is, lozenge 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)
lozenge: a dose of medicine in the form of a small pellet

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

sleeping pill (noun)	lozenge (noun)
a soporific drug in the form of a pill (or tablet or capsule)	a dose of medicine in the form of a small pellet
	a small aromatic or medicated candy