Gasoline and Unleaded petrol

Gasoline noun - A volatile flammable mixture of hydrocarbons (hexane and heptane and octane etc.) derived from petroleum; used mainly as a fuel in internal-combustion engines.

Unleaded petrol and gasoline are semantically related. In some cases you can replace phrase "Unleaded petrol" with "Gasoline", this terms are similar.

Unleaded petrol noun - Gasoline that has not been treated with a lead compound.

Gasoline and unleaded petrol are semantically related. You can use "Gasoline" instead a noun phrase "Unleaded petrol".