birch oil vs sweet-birch oil

birch oil and sweet-birch oil both are nouns.

Word	Noun	Adjective	Verb	Adverb
birch oil	Yes	No	No	No
sweet-birch oil	Yes	No	No	No

As nouns, birch oil and sweet-birch oil are synonyms defined as:

birch oil and sweet-birch oil: a liquid ester with a strong odor of wintergreen; applied externally for minor muscle and joint pain

Other synonyms of birch oil include methyl salicylate.

birch oil (noun)	sweet-birch oil (noun)
a liquid ester with a strong odor of wintergreen; applied externally for minor muscle and joint pain	a liquid ester with a strong odor of wintergreen; applied externally for minor muscle and joint pain