Another difference is that JP
-4 is Naptha based while virtually all others (JP-7 a noteworthy exception) are kerosene based. JP
-8 also has floability additives in addition to Fuel System Icing Inhibitors which will cause transfer pumps and anything else with a neoprene seal to leak like a seive.
When the Air Force bought the KC
-10's they all flew on JP
-4 originally and in the states. When USAFE changed over to JP
-8. We'd go to Europe on deployments and within a week, any marginal seals were leaking like crazy. We'd bring the planes "home" to get them fixed and if we took fuel at any stateside location enroute (JP-4 or JP
-5 didn't matter) the leaks would be all gone by the time troubleshooting could begin.
One more thing; The Navy used JP
-5 which provided a measure of fire safety over JP
-4 on the ships. When JP
-4 mixes with 5 there's a chemical reaction which lowers the flash point to below that of either fuel. We used to get very angry communications from Carrier Air Bosses if they found JP
-4 in any of their planes.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533