Bungleau gave a good explanation, and the hole sizes are different...
The way it was explained to me (when I was fueling aircraft with JP5) is that diesel is like a low refined fuel. JP5 or other jet fuel is more refined. Much higher refinement is for gasoline. Like the difference between coal and diamonds.
From what I understand, you can even use jet fuel in a diesel truck (when you are desperate) and your truck will run funny for a bit till you get it out of the system. Gasoline is way too refined to let the engine run correctly - but it might try for a short time until it seizes.
Basically, don't mix them up and you will be fine.
