Compare all three of your reports, you know, the details. You likely have accounts/negatives/collections reporting on some reports, but not all three bureau's. Everytime I see a different score (by different we're talking more than 10pts) it's because a particular account (good or bad) is only partially reporting (not all three bureau's).
Some creditors also report differently to the bureau's, probably a software thing with poorly trained employees. I can't imagine the amount of time that goes into credit bureau reporting on a daily basis. What a job huh?