fragrancy vs aroma

fragrancy and aroma both are nouns.

Word	Noun	Adjective	Verb	Adverb
fragrancy	Yes	No	No	No
aroma	Yes	No	No	No

As nouns, aroma is a hypernym of fragrancy; that is, aroma is a word with a broader meaning than fragrancy:

Other hypernyms of fragrancy include odor, odour, olfactory property, scent, smell.

fragrancy (noun)	aroma (noun)
a pleasingly sweet olfactory property	any property detected by the olfactory system
	a distinctive odor that is pleasant