leaded petrol vs petrol

leaded petrol and petrol both are nouns.

Word	Noun	Adjective	Verb	Adverb
leaded petrol	Yes	No	No	No
petrol	Yes	No	No	No

As nouns, petrol is a hypernym of leaded petrol; that is, petrol is a word with a broader meaning than leaded petrol:

leaded petrol: gasoline treated with a lead compound to reduce motor knocks
petrol: a volatile flammable mixture of hydrocarbons (hexane and heptane and octane etc.) derived from petroleum; used mainly as a fuel in internal-combustion engines

Other hypernyms of leaded petrol include gas, gasolene, gasoline.

leaded petrol (noun)	petrol (noun)
gasoline treated with a lead compound to reduce motor knocks	a volatile flammable mixture of hydrocarbons (hexane and heptane and octane etc.) derived from petroleum; used mainly as a fuel in internal-combustion engines