What is the difference between Salam and Istisna'a?

The majority of jurists consider istisna' (manufacturing contract) a type of salam (forward contract) and stipulate that its conditions must be met therein. However, the Hanafis differentiate between the two, with each having its own rulings. In salam, the sold item is a debt [due] on the seller, the price is paid at the contract session, deferral is for the purpose of delay, and it applies only to fungible items. As for istisna', the contracted item is a specific asset, and the price may be paid in full, in part, or not at all; deferral is for the purpose of expedition, and it applies to both fungible and non-fungible items. Furthermore, salam is a binding contract, whereas istisna' is not binding before or after manufacturing, except after the commissioning party sees the manufactured item and accepts it. Also, it is not a condition for the capital to be seized in istisna', unlike in salam.