Lenders pull a trimerge from all three bureaus.  The scores that lenders use are the most up to date and accurate.  What you can get online as a consumer is probably older scoring models that are cheaper and often reflect different scores.

There are differences in scoring models used when a Tri-merged report is done. It's unfair to the consumer but that's how these businesses make their money. Go to this link and it gives a pretty good explanation of how the scores are determined and that there are many scoring models. http://www.credit-factor.com/creditscore/96-consumers-know-credit-credit-model