unleaded petrol vs unleaded gasoline

unleaded petrol and unleaded gasoline both are nouns.

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

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

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

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