'Market order' will be executed immediately at the current price offered in the market. Execution of order is guaranteed, but the price at which the order is transacted is not guaranteed. An indicative price is displayed with this order type option.
'Limit order' will only be executed at the price you specify or at a better price, but order may not be filled immediately, or may not be executed. Price is guaranteed, however the order will remain open until filled. The exact price you will pay is displayed with this order type option. Your limit orders remain open unless manually cancelled.
'Immediate Or Cancel' (IOC) order requires all or part of the order to be executed immediately or it will be cancelled. When an IOC order is placed to the system, the order engine will attempt to execute it according to the order specifications. If the order cannot be executed or can only be partially matched, the system will automatically cancel the order or the unexecuted part of the order.