What is the difference between rolling and future indices and commodities?

Rolling (Spot) Contracts
These don’t have an expiry date. You can keep your position open as long as you like- just note that a daily rollover fee is charged to hold the position overnight.

Futures Contracts
These have a set expiry date. Your position will be closed automatically at the contract’s expiry based on the market’s settlement price. When one contract expires, a new one is issued.