Credit Scores different on Myfico vs. Credit Bureau Source

[frugal]

Ok..this is so baffling.  I'm help to building my girlfriends CS and she went to www.equifax.com.  She pulled her report and it gave her Credit Scores from all 3 bureaus.  I told her about myfico and how I loved it for 3 years (especially the forums ).  Anyway, she joined myfico and when she pulled her report it was about 75 points lower than equifax.  So, I got curious, I went to www.equifax.com and join and I got my credit scores from all three bureaus...I almost had a heart attack.  On that site it was stating my EQ= 648, TU=634...on myfico (which I pulled today as well) my score is EQ= 689, TU=701.  I'm not so sure about the source because I get approved for things that warrants a 689 score compared to a 648.  I just can't believe my score from equifax (the source) and its the opposite for my girlfriend..

Can anyone please explain how this is happening and which one should I believe. What are the factors that make the discrepancies?

[llecs]

Equifax offers scores, but they aren't FICO scores. They created their own score and sell that as a FICO knock-off and that FAKO is simply called an "Equifax Credit Score". Ignore thier scores.

Now they do offer an EQ FICO score only. You can get that by subscribing to their version of ScoreWatch and they also sell an EQ FICO with your full report but that link for that score is very difficult to find and they are actively promoting their score. They never sold any EX or TU FICO scores within their site.

The formulas are totally different as are the score ranges (300-850 for FICO vs. their 280-850) . I subscribe to one of their monitoring products now that offer their FAKO score, but I'm not sure what goes into it that FICO doesn't consider or vice-versa.