sleeping tablet vs lozenge

sleeping tablet and lozenge both are nouns.

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

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

sleeping tablet: 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 tablet include pill, tab, tablet, hypnotic, soporific.

sleeping tablet (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