unleaded gasoline vs unleaded petrol

unleaded gasoline and unleaded petrol both are nouns.

Word	Noun	Adjective	Verb	Adverb
unleaded gasoline	Yes	No	No	No
unleaded petrol	Yes	No	No	No

As nouns, unleaded gasoline and unleaded petrol are synonyms defined as:

unleaded gasoline and unleaded petrol: gasoline that has not been treated with a lead compound

unleaded gasoline (noun)	unleaded petrol (noun)
gasoline that has not been treated with a lead compound	gasoline that has not been treated with a lead compound