what is instant buy & how different it is from normal buy button, in case of investing.
Seems like you are referring to Instant Buy / Sell under Trader’s Controls.
When you select - Instant Buy, order is sent immediately to the exchange for execution. When it is on regular, it takes about 2-3 seconds when you have time to modify/cancel the same before sending it to exchange.
Hope this is helpful and what you were looking for.