In Section 28.4 of Hull, it says that Equation (28.21) shows that the forward price of any variable (except an interest rate) is its expected future spot price in a world that is forward risk neutral with respect to P(t, T). Note the difference here between forward prices and futures prices. The argument in Section 18.7 shows that the futures price of a variable is the expected future spot price in the traditional risk-neutral world. My questions are What is the intuition underlying this difference? Is this difference of any significance? In what way?
