They use a different Octane measuring standard. The numbers are different.
Our 87 octane is the same as European 91 octane, so 93 octane is really just like 89 octane in the US.
89 octane was the standard until unleaded gas was introduced.
A-76 very low quality, primarily used for tractors, trucks, some old cars.
A-92 std. quality. Used by old cars and trucks, vans.
A-95 high quality. Used by majority of cars, some vans.
A-98 premium qualty (or superfine?). Used by some cars.