Jet A vs. Jet B depends on how you’re looking at it, by weight or by volume. The following uses numbers from Canada, and I have no idea if European, Aussie, or other fuels are slightly different.
Jet A has a caloric value of 18,300 BTUs/lb.
Jet B has a caloric value of 18,400 BTUs/lb.
Therefore, Jet B has roughly 0.54% more caloric value/lb. , and if you compare by weight, is a slightly more energetic fuel.
On the other hand, Jet A is approx 5.5% heavier than Jet B at 15ºC, so the same volume will weigh in higher. Therefore, if the comparison is by volume, you’ll go further on Jet A than you will on Jet B.
Hope this helps you out.
[This message has been edited by CTD (edited 20 March 2001).]