Jet fuel has an 82 or 100 octane rating. The standard for aviation fuel is 100 octane. There are two types of 100 Avgas: 100 octane, which has an extremely high lead content, and 100 LL, which has a lower amount of up to 0.56 grams of lead per liter.
A lower octane jet fuel is 82 UL, which is designed to work in lower compression aviation engines. An engine that can run on this fuel may also run on unleaded fuel. Avgas is designed specifically for jet engines and can be dyed different colors, such as green for 100, blue for 100 LL and purple for 82 UL.