Jet A and Jet A-1 are kerosene-type fuels. The primary difference between the two is freeze point, the temperature at which wax crystals disappear in a laboratory test.
Jet A, which is mainly used in the United States, must have a freeze point of minus 40ºC or below and does not typically contain static dissipator additive. Jet A-1 must have a freeze point of minus 47ºC or below and for locations outside the United States, this fuel normally contains static dissipator additive. There are other key differences between the manufacturing specification within the United States and Europe/Africa/Middle East/Australasia.
Def. Stan. 91-91 has an additional requirement for lubricity for Jet A-1.
ExxonMobil Jet A and ExxonMobil Jet A-1 meet the requirements of ASTM D1655 Standard Specification for Aviation Turbine Fuels. ExxonMobil Jet A-1 also complies with U.K. DEF STAN 91-91, and the JIG (Joint Inspection Group) Aviation Fuel Requirements for Jointly Operated Systems (Check List). In all cases, the most recent issue of relevant specifications applies to the product supplied.