aroma vs odor

aroma and odor both are nouns.

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

As nouns, aroma and odor are synonyms defined as:

Other synonyms of aroma include odour, olfactory property, scent, smell.

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

aroma: a distinctive odor that is pleasant
odor: the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form

Other hypernyms of aroma include odour, olfactory perception, olfactory sensation, smell.

aroma (noun)	odor (noun)
any property detected by the olfactory system	any property detected by the olfactory system
a distinctive odor that is pleasant	the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form