Each CRA requests its own scoring formula, and each rewards and penalizes different things. Off the cuff, I would say that EQ is harsher on lates, and EX is harsher on inqs and new accounts and low average history.
TU seems to love it if you have a mortgage, but they are more likely than the others to ding you for having more than one or two CC's reporting balances. In fact, my TU score actually increased when all my cards had a $0 balance on the TU report. (This resulted from TU's complete inability to be current on reports, so they missed one card that did have a balance.)
Otherwise, it's the usual what's-different-on-your-TU-report.
For me, EQ has always been lowest, but it's higher now, because I'm disputing a balance on EQ only, and that account has some lates, so it's temporarily not counting.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007