My Bank of America credit card shows me a "FICO credit score powered by TransUnion". I also have an account with CreditSesame which shows me a "credit score powered by TransUnion" (No FICO is mentioned). The Credit Sesame score is consistently ~60 points higher than the score I see through BoA. Most months they move together (both go up/down) but sometimes they move in different directions.
Why are these not equal?
Bank of America offers their credit card customers free monthly FICO credit scores. The FICO score is the credit score that is used by most lenders for determining credit worthiness. The score is obtained using a secret proprietary formula.
CreditSesame, CreditKarma, and other free credit monitoring websites offer VantageScore credit scores, a competitor of FICO that uses a different formula.
Your credit report with each of the three credit bureaus (Experian, Equifax, and TransUnion) contain your credit history data. This data can be used as inputs for any credit score formula. Both Bank of America and CreditSesame are using your TransUnion report as inputs for their score formulas, but since the formulas are different, they yield different scores.
You see a difference because they are two different scores. They both use TransUnion data in their calculations but have different scoring algorithms, leading to a different score. It is generally recommended to pay little attention to non-FICO scores since most lenders will use a FICO score and as you have seen, they can be substantially different.
