Just because your credit score is 705, that does not mean that you are a low risk consumer.
Yes, a 705 is a very strong credit score. The lender is going to look further than your credit score. Do you have rental history? Mortgage history? Do you have multiple tradelines? How old are your tradelines? Are they 6 months old? 2 years? 5 years? Do you only have a credit card? Are you diverse with a few credit card and an auto payment? Do you have good job history? Have you never worked?
Also, how many people have pulled your credit in the past 6 months? a year? Inquiries ding your score. Revolving balances above 50% of the limit ding your score. There is so much that is involved.
Also, a 650 on transunion is the same as a 650 on experian. If I pull a report and see a 650...it is a 650. I do not know about consumer credit for student loans, but mortgages pull all the repositories, and use the middle score.