Options and futures are both contracts under which you agree to buy or sell an asset at a later date, but the main difference is that options offer you just that – an option to buy. You have to pay a premium for an option, but in return you are not obligated to do anything: you can choose to buy the agreed-upon assets at any time during the period set out in the contract, but you are never required to do so.
Futures contracts come with no premium attached, but they do impose obligations on both buyer and seller. When the predetermined time comes, the buyer absolutely must buy the assets, and the seller must sell them. In addition, the value of the assets used in futures contracts are usually greater than those used for options, so there’s much more risk in a futures contract: by the time you have to buy (or sell) your assets, their value may have changed dramatically, for better or for worse, but you still have to buy (or sell) at the price agreed upon when the futures contract was drawn up.