Your Amex score is a true Experian FICO 08 score.
Your Credit Karma scores are TransUnion Vantagescore 3.0 and Equifax Vantagescore 3.0.
The score you get from Amex and the ones from CK are not related at all. The majority of lenders use FICO scores, so I'd value your score through Amex more. Unless a potential lender of yours is using Vantagescore 3.0, I wouldn't care about those scores very much.
