Why does the bank have much lower credit score?

Credit reports will vary on the institution that is pulling the credit. Mortgage credit reports are much more detailed than other credit reports. Also, when you request your personal credit, they call that a soft pull. There are tons of factors with credit. It could also be on one day, your revolving debt was high, then the following credit report reflected a payment on the account. If you are looking for a mortgage loan, above 700 is good, but you could pay more in interest if you have a high loan to value, or a high loan balance.

Indeed, credit scores are fixed at a point in time, only to change the next time. There are so many factors to take into consideration - a mere inquiry will have an impact, or that a creditor hasn't posted the most recent payment yet might drop a score a few points; and of course if you've added to any balances, that'll always make a difference.

Oops...this, too: the score that a credit repository gives you is always going to be different from the one that a creditor sees. Precisely why is that? I don't have that answer, but you can dig around on myfico(dot)com and find that out, perhaps.

>>I contact Equifax they tell me its 750, Why?

Because the Credit Bureau's provide "consumer" credit scores, and the credit reports Mortgage companies use provide "FICO" credit scores. And consumer credit scores are always higher. To receive the exact same score your Lender will see, you need to use www.myfico.com. Synch with your Loan Officer, and access your scores on the same day, and they'll be the same.