athar vs essential oil

athar and essential oil both are nouns.

Word	Noun	Adjective	Verb	Adverb
athar	Yes	No	No	No
essential oil	Yes	No	No	No

As nouns, essential oil is a hypernym of athar; that is, essential oil is a word with a broader meaning than athar:

athar: essential oil or perfume obtained from flowers
essential oil: an oil having the odor or flavor of the plant from which it comes; used in perfume and flavorings

Other hypernyms of athar include volatile oil.

athar (noun)	essential oil (noun)
essential oil or perfume obtained from flowers	an oil having the odor or flavor of the plant from which it comes; used in perfume and flavorings