sleeping capsule vs sleeping tablet

sleeping capsule and sleeping tablet both are nouns.

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

As nouns, sleeping capsule and sleeping tablet are synonyms defined as:

sleeping capsule and sleeping tablet: a soporific drug in the form of a pill (or tablet or capsule)

Other synonyms of sleeping capsule include sleeping draught, sleeping pill.

sleeping capsule (noun)	sleeping tablet (noun)
a soporific drug in the form of a pill (or tablet or capsule)	a soporific drug in the form of a pill (or tablet or capsule)