oil of wintergreen vs wintergreen oil

oil of wintergreen and wintergreen oil both are nouns.

Word	Noun	Adjective	Verb	Adverb
oil of wintergreen	Yes	No	No	No
wintergreen oil	Yes	No	No	No

As nouns, oil of wintergreen and wintergreen oil are synonyms defined as:

oil of wintergreen and wintergreen oil: oil or flavoring obtained from the creeping wintergreen or teaberry plant

oil of wintergreen (noun)	wintergreen oil (noun)
oil or flavoring obtained from the creeping wintergreen or teaberry plant	oil or flavoring obtained from the creeping wintergreen or teaberry plant