GTT (Good-Till-Triggered) orders are triggered based on the Last Traded Price (LTP) of a specific instrument. In contrast, ATO (Alert-Triggered Orders) allows you to place orders based on multiple parameters, such as LTP, High, Low, Open, and total buy quantity.
Additionally, GTT can only place a single order for the specified instrument. However, ATO enables you to trigger a basket of orders, allowing you to take positions in stocks or options based on the movement of the index or other instruments.