The TOT at DCA is actually "smaller" in actual movement-wise than the TOT at WDW. At DCA, the elevator will initially "lunge" backwards into the actual drop shaft amid lightening and narration from Rod Serling. It will then move up the shaft...doors open and you will see a new 'mirror' effect that is rumored to be pretty cool in which you are 'shown' being sucked into the Twilight Zone. This is complete with violent shaking of the elevator car that supposedly is much more than what is capable in WDW's TOT. The elevator will then move to the next show scene...doors open and it is an exact duplicate of the hallway scene at WDW with the ghosts and such. Rumored to end differently than our window smashing finale, the elevator suddenly drops and goes into, I beleive, the drop profile from TOT version 2 (or maybe 3). The drops stop and you see another new "mini-scene" and the elevator moves forward out of the drop shaft. Supposedly DCA's TOT has a lot more storytelling to it as their is A LOT more narration in it than WDW's TOT.
As you might have realized, DCA's tower does not have the 5th dimension room (the part where the elevator at WDW's TOT moves from the 'lift shaft' to the actual 'drop shaft') Depending on who you talk to you will hear two different reasons for eliminating it. The first is that apparently the Imagineers have never been pleased with how the 5th dimension room turned out. Apparently they wanted it to come across as though you were floating through that room but due to sensors for the ride and such...some of the effects had to be removed and it has never lived up to the Imagineer's initial plans. Thus, when designed the DCA Tower they produced a new, different, yet equally cool effect (the mirror thing) to replace that. The other theory is that DCA's tower is a 'cheaper' version of WDW's as it does not have the movement. However, as I described above, the elevator still has the ability to move forward and backwards into and out of the drop shaft....so it seems foolish to me to think that cost was the major driving factor...it might have been somewhat of a reason but surely NOT the whole reason.
Since DCA's tower does not include two different shafts for the 'lift' and the 'drop', their tower has 3 drop shafts instead of our two. There will also be two loading levels in the boiler room to help with the capacity issues faced by using only one shaft for everything. Apparently their boiler room is MUCH larger than WDW's. As the one in WDW has a point where the line splits, so will DCA's, but half of it will go up stairs and across a catwalk themed walkway suspended from the top of the boiler room. Pics and video make it look amazing. This may be the reason the 'base' of DCA's Tower looks bigger...maybe not.
Other than that, the two Towers are pretty similar beyond the obvious change in arcitectural style...both have similar lobbies (our roof is "domed", DCA's is flat though), similar pre-show areas, similar retail area..etc.
