Diesel has a stronger odor to most, and being oily, sticks to your hands more than gasoline, and hangs around on stuff more, e.g., if s bit of gasoline gets on the handle of a gasoline nozzle, it mostly evaporates in a minute or two, but if a bit of diesel gets on the nozzle handle, it hangs around for a while like oil would. Take a look at the ground near a diesel pump vs. a gasoline pump to see the difference in what evaporates and what stays.