CreditKarma score is significantly different than FICO score
I am fairly new to credit as I opened my first credit card last August. While I have paid the card off on time each billing cycle, I had a bill from a hospital visit back in 2017 go into collections which has impacted my credit score. BoA shows my FICO score as 617 while CreditKarma has it at 741. Pretty big discrepancy IMO. After a few google and reddit searches, it appears as if I am not alone as other people have reported similar issues. However, their scores were usually off by 10-50 points, not as big of a deficit as mine.
I understand CreditKarma uses the Vantage 3.0 which is a different scoring method than FICO but I am still curious as to the large gap in the scores. Which score will lenders most likely use when I apply for a mortgage and other cards? Is there a score I should rely more on to gauge my financial health or is this one of those instances where both scores are taken into account and should be viewed equally?
22M, working full time.