Differences in Credit Score

Why is it that when I check my credit score I see 700+ and when my mortgage company checks it the tell me it is in the low 600s?

Wow, that is really unfair. This seems just another example of how stupid a credit score is, when they can’t even narrow it down to one reliable source. I would open wherever you are checking your score to get the 700 and show it to someone at your mortgage company and make them explain why there is such a difference.