Spot trading means buying or selling the actual asset for immediate settlement; the buyer owns the asset afterward. Futures trading means entering a contract whose value is derived from the asset's price, without necessarily owning the asset itself.
Futures allow leverage and the ability to position for both rising and falling prices, and they introduce mechanics such as margin, funding, and in some cases expiry. Spot positions have no funding payments or liquidation in the derivatives sense, since the trader holds the asset directly.
Comparing spot and futures activity helps describe where market interest and risk are concentrated. Differences between spot prices, futures prices, and the volumes in each market are routinely analyzed to understand how leveraged and unleveraged participants are behaving.