Well, margin trading on the spot is when you borrow money from the exchange to buy more crypto than you can afford.
You deposit part of your money — this is the collateral (margin). The exchange adds credit (leverage) to your funds. If the price goes up — you earn more. If it goes down — you can even lose your collateral.
Margin trading is suitable only for experienced traders, as the risks are high.
It shouldn't be compared to futures, as they are not the same.
Both instruments allow the use of leverage, but the mechanics and risks are different.