Interest rates vary among the many different programs.
Although the spread for one loan may be smaller, that doesn't necessarily mean you're getting the best rate available, so you may want to shop around first. Another thing to look out for is whether the spread increases at repayment. You may be getting a good deal while you are enrolled in school, but that rate may go up when you begin repayment. Keep in mind that this increased spread affects the entire balance of your loan for the remainder of your repayment period. This means that you will pay more in interest over the life of your loan.