Start by getting all 3 full credit reports from www.annualcreditreport.com. It could be that Transunion contains information that is different from the other reports (such as, a legitimate account that is not listed on your other reports, or a mistake where your other reports are correct.)
Mistakes and inaccurate information can be appealed, but be aware that accurate information can't be removed no matter what "credit repair" companies claim.
Then, understand you have over 50 different "official" FICO credit scores. FICO offers different mathematical models. The most common is "FICO 8", and you can have 3 different FICO 8 scores if the information at the 3 credit bureaus is slightly different. Your general credit score goes from 300-850, but there are also specialty scores focused on particular lending sectors (like credit cards, mortgages and car loans) that use different mathematical models and those scores go from 250-900. And some lenders prefer the older FICO model 3 or 5. So your score can be calculated in lots of different ways.
Also, the score provided by the Turbo® app or website is a Transunion "Vantagescore" which is similar to but not the same as your FICO score. To get access to your FICO scores, you will need to buy a subscription somewhere. (Some credit cards will give you a score for free. You need to be careful what you're looking at. American Express gives an Experian FICO 8 score, Citibank gives an Equifax Bankcard FICO 8 score, and Chase gives a VantageScore, so they're all different for the same person.)
Finally, a 5-10 point difference is not really meaningful anyway. If your FCIO 8 scores are 703, 703 and 698, that all indicates you are a "good" borrower, and an average credit risk. If you needed to borrow money and a lender was going to pop your interest rate because 700 is their cutoff and one out of three scores is lower, go find another lender.
