At DHS there are 23 different versions (how the elevator does the drops) of the ride. DCA only has one version. They are completely random - the computer basically picks which version will be done. Some feel like you are on a trampoline bouncing up and down, some drop down, shoot back to the top and repeat a few more times. Those are my faves - you get great airtime over and over again!

Like a PP mentioned, a door opens and the elevator actually moves inside of the building before clicking into place and beginning the drops. It is an awesome effect. It is scarier than the one at DCA. If you did not like DCA, you really will not enjoy this one. I would always say to try it once though.
*Update*I went to verify the # of drop sequences - turns out that it is in fact totally random, so there is not technically a # of different sequences.