Spoiler warning! If you've never experienced the attraction, and you'd prefer to be kept in the dark until you do board it, you'll want to bypass the spoilers that follow.
Below you will find a comparison between the Tower of Terror at the Disney-MGM Studios and the Tower iof Terror at Disney's California Adventure.
Here's what guests in Florida experience...Just before the elevator cabin begins its gut-wrenching drops and rises, Florida passengers experience what is known as the "Fifth Dimension." The car's doors open, lights illuminate a hallway, and the elevator slowly, incredibly moves forward into the hallway. As the Twilight Zone theme music plays, bizarre scenes that are part Rod Serling and part Salvador Dali appear on either side of the elevator, including a huge eyeball, a door to nowhere, and the five apparitions from earlier in the ride. The elevator moves towards a star field at the end of the hallway. The stars disappear, and a huge vertical line takes its place. The line splits, revealing a second elevator shaft. The cabin moves into the shaft, everything becomes pitch black, and Rod Serling intones, "You are about to discover what lies beyond the fifth dimension. Beyond the deepest, darkest corner of the imagination...in the Tower of Terror." The faster-than-gravity freefalling mania ensues.
In California, guests experience this...Called the "Looking Glass," the elevator doors open to reveal a stately table with a large mirror above it. Rod Serling invites the passengers to wave at themselves; however, the reflections, still waving and responding in perfect synch with the guests aboard the elevator, morph into ghostly images. Then the ghosts disappear altogether leaving an empty elevator.
California has two cabins per shaft. While one car is loading, another car is experiencing the ride. That's why the cabins have some limited horizontal movement; one car moves a few feet out of the shaft into the loading and unloading areas thereby allowing the other car to move vertically in the shaft. This also explains why, unlike Florida's single boarding floor, the California version loads on two levels.
Florida has a series of random drop sequences. The Florida ride has gone through a series of drop programs through the years. Now, a computer randomly selects the cycle, so you'll never know what you will experience. But every sequence includes a healthy dose of drops, rises, and false starts. The California version offers the identical program on every ride, but it includes a bunch of drops, rises, and false starts. (When the Florida Tower first opened its ride sequence only included a couple of drops and rises.)
A few other minor differences.