In futures trading, you take buy/sell positions in index or stock(s) contracts expiring in different months. If, during the course of the contract life, the price moves in your favor (rises in case you have a buy position or falls in case you have a sell position), you make a profit. In case the price movement is adverse, you incur a loss.
To take the buy/sell position on index/stock futures, you have to place certain % of order value as margin. With futures trading, you can leverage on your trading limit by taking buy/sell positions much more than what you could have taken in cash segment. However, the risk profile of your transactions goes up.
While buy/sell transactions in margin segment have to be squared off on the same day, buy/sell position in the futures segment can be continued till the expiry of the respective contract and squared off any time during the contract life.
Margin positions can even be converted to delivery if you have the requisite trading limits in case of buy positions and required number of shares in your DP in case of sell position. There is no such facility available in case of futures position, since all futures transactions are cash settled as per the current regulations. If you wish to convert your future positions into delivery position, you will have to first square off your transaction in future market and then take cash position in cash market.
Another important difference is the availability of even index contracts in futures trading. You can even buy/sell NIFTY in case of futures in NSE, whereas in case of margin, you can take positions only in stocks
In options trading, you take buy/sell positions in index or stock(s) contracts expiring in different months with various Strike Price. Strike price is the Price at which the underlying Asset is Agreed to be Bought or sold. Premium is the downpayment the Buyer of Call or Put is required to make for entering the options agreement.
In case of Futures the Buyer has an unlimited loss or profit potential whereas the buyer of an option has an unlimited profit and Limited downside. The Seller of a Futures has an Unlimited loss or profit potential but the seller of an option has a Limited profit but Unlimited Downside.