It depends.
Please see the link below for more information from the IRS regarding refunds. There are several topics regarding routing numbers and banking information that may narrow down why the deposit was sent to a different account and what you can do to rectify it in the future.
Refund inquiries
If you elected to pay your TurboTax fees with your refund, this may also account for the different account number. Please see the link below for more information on this service.
Refund processing service
Who provides Pay With My Refund