Forex and futures are two different markets, though they do have some similarities. For instance, the pattern of trading on the two markets is similar, but there is a great difference when it comes to things that are traded on the markets. Forex is an international market where currency pairs are traded. By trading currency pairs, I mean the exchange of currency of one country for the currency of another country.
Traders on forex take advantage of the rise and fall of one currency against the other. On the other hand, futures are also similar, but it's basically the trading of futures contracts that will be delivered at a particular price at a certain date in the future.
Forex is currently the biggest liquid market in the world because its daily trading volume is about $5 trillion, whereas the daily trading volume of futures is less than that of forex.