pastille vs cough drop

pastille and cough drop both are nouns.

Word	Noun	Adjective	Verb	Adverb
pastille	Yes	No	No	No
cough drop	Yes	No	No	No

As nouns, pastille and cough drop are synonyms defined as:

Other synonyms of pastille include pastil, troche.

pastille (noun)	cough drop (noun)
a medicated lozenge used to soothe the throat	a medicated lozenge used to soothe the throat