[daveslash]

FICO is an acronym for Fair, Isaac, and Company. Their "FICO Score" is a piece of software that they make and sell. I'm sure the details are a little more complicated than I'm making it sound, but it's essentially software which is sold. Just like any software, there are different versions - and it's possible to get stuck on an old version if you don't pay for updates. There's FICO 98 (from 1998), FICO 04 (2004), FICO 8 (2008) and FICO 9 (2014). [1][2].

The FICO Software is a scoring engine which will produce an output based on the input you provide it. The three big credit bureaus collect data about you and feed it into the FICO Score software. Even if they all have the same version of the FICO software, because each bureau might have slightly different data on you, your score may be different from each one. Presumably, the FAKO companies also have the FICO Score software, but a much more limited set of data to feed into it - thus making the score less reliable to someone looking to issue you a loan (Big Bank).

At least, that is my understanding of how it works - admittedly, I may be mistaken and welcome corrections.

[1] https://en.wikipedia.org/wiki/Credit_score_in_the_United_Sta... [2] http://www.fico.com/en/02-02-2015-fico-makes-additional-fico...