Point of Recognition:
There is a broad difference in the point of time when one will recognize the revenue.
As per the AS, Revenue is to be recognized either at a point in time when the customer obtains control over the promised service. At times it can be recognized over a period of time as the customer obtains control over the promised service.
Under the GST, the time of supply is triggered when the invoice is raised, or payment is made whichever is earlier. This might lead to a situation wherein GST would be paid on the contract as per the date of invoice, but the revenue would not be recognized in the books because the customer may not have obtained necessary benefits from the contract.